#include <bits/stdc++.h>
using namespace std;
template <class T>
inline void gmin(T &x, const T &y) {
  if (x > y) x = y;
}
template <class T>
inline void gmax(T &x, const T &y) {
  if (x < y) x = y;
}
const int BufferSize = 1 << 16;
char buffer[BufferSize], *Bufferhead, *Buffertail;
bool Terminal;
inline char Getchar() {
  if (Bufferhead == Buffertail) {
    int l = fread(buffer, 1, BufferSize, stdin);
    if (!l) {
      Terminal = 1;
      return 0;
    }
    Buffertail = (Bufferhead = buffer) + l;
  }
  return *Bufferhead++;
}
template <class T>
inline bool read(T &x) {
  x = 0;
  char c = Getchar(), rev = 0;
  while (c < '0' || c > '9') {
    rev |= c == '-';
    c = Getchar();
    if (Terminal) return 0;
  }
  while (c >= '0' && c <= '9') x = x * 10 + c - '0', c = Getchar();
  if (c == '.') {
    c = Getchar();
    double t = 0.1;
    while (c >= '0' && c <= '9')
      x = x + (c - '0') * t, c = Getchar(), t = t / 10;
  }
  x = rev ? -x : x;
  return 1;
}
template <class T1, class T2>
inline bool read(T1 &x, T2 &y) {
  return read(x) & read(y);
}
template <class T1, class T2, class T3>
inline bool read(T1 &x, T2 &y, T3 &z) {
  return read(x) & read(y) & read(z);
}
template <class T1, class T2, class T3, class T4>
inline bool read(T1 &x, T2 &y, T3 &z, T4 &w) {
  return read(x) & read(y) & read(z) & read(w);
}
inline bool reads(char *x) {
  char c = Getchar();
  while (c < 33 || c > 126) {
    c = Getchar();
    if (Terminal) return 0;
  }
  while (c >= 33 && c <= 126) (*x++) = c, c = Getchar();
  *x = 0;
  return 1;
}
template <class T>
inline void print(T x, const char c = '\n') {
  if (!x) {
    putchar('0');
    putchar(c);
    return;
  }
  if (x < 0) putchar('-'), x = -x;
  int m = 0, a[20];
  while (x) a[m++] = x % 10, x /= 10;
  while (m--) putchar(a[m] + '0');
  putchar(c);
}
const int inf = 0x3f3f3f3f;
const int N = 4005, M = 100005, mod = 1e9 + 7;
template <class T, class S>
inline void ch(T &x, const S y) {
  x = (x + y) % mod;
}
inline int exp(int x, int y, const int mod = ::mod) {
  int ans = 1;
  while (y) {
    if (y & 1) ans = (long long)ans * x % mod;
    x = (long long)x * x % mod;
    y >>= 1;
  }
  return ans;
}
int n, a[N], sum[N], f[4][N][95];
inline int g(int i, int j, int k) {
  int x = j + i, y = j + k;
  if (x + y + i > n) return sum[x] - (sum[n] - sum[n - y]);
  if (x + y + i + 1 <= n)
    return min(f[i & 3][j + i][k], f[i + 1 & 3][j + i][k + 1]);
  return f[i & 3][j + i][k];
}
int main() {
  scanf("%d", &n);
  int mx = 1;
  while ((long long)(mx + 1) * (mx + 2) / 2 <= n) mx++;
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]), sum[i] = sum[i - 1] + a[i];
  for (int i = mx; i; i--) {
    for (int j = n / 2; j >= 0; j--)
      for (int k = 0; k <= i; k++) {
        if (j * 2 + k > n) break;
        if (j * 2 + k + i > n)
          f[i & 3][j][k] = sum[j] - (sum[n] - sum[n - j - k]);
        else if (j * 2 + k + i + 1 <= n)
          f[i & 3][j][k] = max(g(i, j, k), g(i + 1, j, k));
        else
          f[i & 3][j][k] = g(i, j, k);
      }
  }
  printf("%d\n", f[1][0][0]);
  return 0;
}
