#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
void *wmem;
template <class T>
inline void walloc1d(T **arr, int x, void **mem = &wmem) {
  static int skip[16] = {0, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1};
  (*mem) = (void *)(((char *)(*mem)) + skip[((unsigned long long)(*mem)) & 15]);
  (*arr) = (T *)(*mem);
  (*mem) = ((*arr) + x);
}
struct mint {
  static unsigned R, RR, Rinv, W, md, mdninv;
  unsigned val;
  mint() {}
  mint(int a) { val = mulR(a); }
  mint(unsigned a) { val = mulR(a); }
  mint(long long a) { val = mulR(a); }
  mint(unsigned long long a) { val = mulR(a); }
  int get_inv(long long a, int md) {
    long long e, s = md, t = a, u = 1, v = 0;
    while (s) {
      e = t / s;
      t -= e * s;
      u -= e * v;
      swap(t, s);
      swap(u, v);
    }
    if (u < 0) {
      u += md;
    }
    return u;
  }
  void setmod(unsigned m) {
    int i;
    unsigned t;
    W = 32;
    md = m;
    R = (1ULL << W) % md;
    RR = (unsigned long long)R * R % md;
    switch (m) {
      case 104857601:
        Rinv = 2560000;
        mdninv = 104857599;
        break;
      case 998244353:
        Rinv = 232013824;
        mdninv = 998244351;
        break;
      case 1000000007:
        Rinv = 518424770;
        mdninv = 2226617417U;
        break;
      case 1000000009:
        Rinv = 171601999;
        mdninv = 737024967;
        break;
      case 1004535809:
        Rinv = 234947584;
        mdninv = 1004535807;
        break;
      case 1007681537:
        Rinv = 236421376;
        mdninv = 1007681535;
        break;
      case 1012924417:
        Rinv = 238887936;
        mdninv = 1012924415;
        break;
      case 1045430273:
        Rinv = 254466304;
        mdninv = 1045430271;
        break;
      case 1051721729:
        Rinv = 257538304;
        mdninv = 1051721727;
        break;
      default:
        Rinv = get_inv(R, md);
        mdninv = 0;
        t = 0;
        for (i = 0; i < ((int)W); i++) {
          if (t % 2 == 0) {
            t += md;
            mdninv |= (1U << i);
          }
          t /= 2;
        }
    }
  }
  unsigned mulR(unsigned a) { return (unsigned long long)a * R % md; }
  unsigned mulR(int a) {
    if (a < 0) {
      a = a % md + md;
    }
    return mulR((unsigned)a);
  }
  unsigned mulR(unsigned long long a) { return mulR((unsigned)(a % md)); }
  unsigned mulR(long long a) {
    a %= md;
    if (a < 0) {
      a += md;
    }
    return mulR((unsigned)a);
  }
  unsigned reduce(unsigned T) {
    unsigned m = T * mdninv,
             t = (unsigned)((T + (unsigned long long)m * md) >> W);
    if (t >= md) {
      t -= md;
    }
    return t;
  }
  unsigned reduce(unsigned long long T) {
    unsigned m = (unsigned)T * mdninv,
             t = (unsigned)((T + (unsigned long long)m * md) >> W);
    if (t >= md) {
      t -= md;
    }
    return t;
  }
  unsigned get() { return reduce(val); }
  mint &operator+=(mint a) {
    val += a.val;
    if (val >= md) {
      val -= md;
    }
    return *this;
  }
  mint &operator-=(mint a) {
    if (val < a.val) {
      val = val + md - a.val;
    } else {
      val -= a.val;
    }
    return *this;
  }
  mint &operator*=(mint a) {
    val = reduce((unsigned long long)val * a.val);
    return *this;
  }
  mint &operator/=(mint a) { return *this *= a.inverse(); }
  mint operator+(mint a) { return mint(*this) += a; }
  mint operator-(mint a) { return mint(*this) -= a; }
  mint operator*(mint a) { return mint(*this) *= a; }
  mint operator/(mint a) { return mint(*this) /= a; }
  mint operator+(int a) { return mint(*this) += mint(a); }
  mint operator-(int a) { return mint(*this) -= mint(a); }
  mint operator*(int a) { return mint(*this) *= mint(a); }
  mint operator/(int a) { return mint(*this) /= mint(a); }
  mint operator+(long long a) { return mint(*this) += mint(a); }
  mint operator-(long long a) { return mint(*this) -= mint(a); }
  mint operator*(long long a) { return mint(*this) *= mint(a); }
  mint operator/(long long a) { return mint(*this) /= mint(a); }
  mint operator-(void) {
    mint res;
    if (val) {
      res.val = md - val;
    } else {
      res.val = 0;
    }
    return res;
  }
  operator bool(void) { return val != 0; }
  operator int(void) { return get(); }
  operator long long(void) { return get(); }
  mint inverse() {
    int a = val, b = md, t, u = 1, v = 0;
    mint res;
    while (b) {
      t = a / b;
      a -= t * b;
      swap(a, b);
      u -= t * v;
      swap(u, v);
    }
    if (u < 0) {
      u += md;
    }
    res.val = (unsigned long long)u * RR % md;
    return res;
  }
  mint pw(unsigned long long b) {
    mint a(*this), res;
    res.val = R;
    while (b) {
      if (b & 1) {
        res *= a;
      }
      b >>= 1;
      a *= a;
    }
    return res;
  }
  bool operator==(int a) { return mulR(a) == val; }
  bool operator!=(int a) { return mulR(a) != val; }
};
mint operator+(int a, mint b) { return mint(a) += b; }
mint operator-(int a, mint b) { return mint(a) -= b; }
mint operator*(int a, mint b) { return mint(a) *= b; }
mint operator/(int a, mint b) { return mint(a) /= b; }
mint operator+(long long a, mint b) { return mint(a) += b; }
mint operator-(long long a, mint b) { return mint(a) -= b; }
mint operator*(long long a, mint b) { return mint(a) *= b; }
mint operator/(long long a, mint b) { return mint(a) /= b; }
inline void rd(int &x) {
  int k, m = 0;
  x = 0;
  for (;;) {
    k = getchar();
    if (k == '-') {
      m = 1;
      break;
    }
    if ('0' <= k && k <= '9') {
      x = k - '0';
      break;
    }
  }
  for (;;) {
    k = getchar();
    if (k < '0' || k > '9') {
      break;
    }
    x = x * 10 + k - '0';
  }
  if (m) {
    x = -x;
  }
}
inline void wt_L(char a) { putchar(a); }
inline void wt_L(int x) {
  char f[10];
  int m = 0, s = 0;
  if (x < 0) {
    m = 1;
    x = -x;
  }
  while (x) {
    f[s++] = x % 10;
    x /= 10;
  }
  if (!s) {
    f[s++] = 0;
  }
  if (m) {
    putchar('-');
  }
  while (s--) {
    putchar(f[s] + '0');
  }
}
inline void wt_L(mint x) {
  int i;
  i = (int)x;
  wt_L(i);
}
struct combination_mint {
  mint *fac, *ifac;
  void init(int n, void **mem = &wmem) {
    int i;
    walloc1d(&fac, n, mem);
    walloc1d(&ifac, n, mem);
    fac[0] = 1;
    for (i = (1); i < (n); i++) {
      fac[i] = fac[i - 1] * i;
    }
    ifac[n - 1] = 1 / fac[n - 1];
    for (i = n - 2; i >= 0; i--) {
      ifac[i] = ifac[i + 1] * (i + 1);
    }
  }
  mint C(int a, int b) {
    if (b < 0 || b > a) {
      return 0;
    }
    return fac[a] * ifac[b] * ifac[a - b];
  }
  mint P(int a, int b) {
    if (b < 0 || b > a) {
      return 0;
    }
    return fac[a] * ifac[a - b];
  }
  mint H(int a, int b) {
    if (a == 0 && b == 0) {
      return 1;
    }
    if (a <= 0 || b < 0) {
      return 0;
    }
    return C(a + b - 1, b);
  }
};
char memarr[96000000];
unsigned mint::R, mint::RR, mint::Rinv, mint::W, mint::md, mint::mdninv;
int N;
int M;
mint dp1[2001][2001];
combination_mint comb;
inline mint f(int a, int b) {
  if (a < b) {
    return 0;
  }
  return (a - b + 1) * comb.C(a + b, b) / (a + 1);
}
int main() {
  int i, j, k, x1, x2, y1, y2;
  mint res, tmp1, tmp2;
  wmem = memarr;
  {
    mint x;
    x.setmod(998244853);
  }
  rd(N);
  rd(M);
  comb.init(5000);
  res = 0;
  for (i = 0; i < (N + M + 1); i++) {
    for (j = i % 2; j <= N; j += 2) {
      x1 = j + (i - j) / 2;
      y1 = (i - j) / 2;
      if (x1 < 0 || y1 < 0 || x1 > N || y1 > M) {
        continue;
      }
      x2 = y2 = 0;
      if (i < N + M) {
        x2 = N - x1;
        y2 = M - y1 - 1;
        if (y2 < 0) {
          continue;
        }
      }
      res += j * f(x1, y1) * f(y2, x2);
    }
  }
  wt_L(res);
  wt_L('\n');
  return 0;
}
