#include <bits/stdc++.h>
#pragma GCC optimize("Ofast", "unroll-loops", "omit-frame-pointer", "inline")
#pragma GCC option("arch=native", "tune=native", "no-zero-upper")
#pragma GCC target("avx2")
using namespace std;
template <typename T>
void maxtt(T& t1, T t2) {
  t1 = max(t1, t2);
}
template <typename T>
void mintt(T& t1, T t2) {
  t1 = min(t1, t2);
}
bool debug = 0;
int n, m, k;
int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0};
string direc = "RDLU";
const long long MOD2 = (long long)998244353 * (long long)998244353;
long long ln, lk, lm;
void etp(bool f = 0) {
  puts(f ? "YES" : "NO");
  exit(0);
}
void addmod(int& x, int y, int mod = 998244353) {
  x += y;
  if (x >= mod) x -= mod;
  if (x < 0) x += mod;
  assert(x >= 0 && x < mod);
}
void et(int x = -1) {
  printf("%d\n", x);
  exit(0);
}
long long fastPow(long long x, long long y, int mod = 998244353) {
  long long ans = 1;
  while (y > 0) {
    if (y & 1) ans = (x * ans) % mod;
    x = x * x % mod;
    y >>= 1;
  }
  return ans;
}
long long gcd1(long long x, long long y) { return y ? gcd1(y, x % y) : x; }
long long a[200135], b[200135], SZ, P, R;
vector<char> ans;
void addo(char x, long long cnt) {
  if (x == 'P')
    P += cnt;
  else
    R += cnt;
  SZ += cnt;
  if (SZ > 500000) return;
  for (int(i) = 0; (i) < (int)(cnt); (i)++) ans.push_back(x);
}
void etn() {
  puts("IMPOSSIBLE");
  exit(0);
}
void ppt() {
  if (P > 200000) {
    puts("BIG");
    printf("%lld\n", P);
  } else {
    printf("SMALL\n%lld\n", SZ);
    for (int i = (int)SZ - 1; i >= 0; i--) printf("%c", ans[i]);
  }
  exit(0);
}
void cal2() {
  if (b[1] > b[2]) {
    addo('R', 1);
    swap(b[1], b[2]);
  }
  bool rev = 0;
  if (a[1] > a[2]) {
    rev = 1;
    swap(a[1], a[2]);
  }
  if (a[1] == b[1]) {
    if (b[2] >= a[2] && (b[2] - a[2]) % a[1] == 0) {
      long long cnt = (b[2] - a[2]) / a[1];
      addo('P', cnt);
      if (rev) addo('R', 1);
      ppt();
    } else
      etn();
  }
  long long cc = b[2] / b[1];
  b[2] %= b[1];
  if (b[2] == 0) etn();
  addo('P', cc);
  addo('R', 1);
  swap(b[1], b[2]);
  if (rev) swap(a[1], a[2]);
  cal2();
}
void calmore() {
  bool asc = 1, dec = 1, sm = 1;
  for (int(i) = 1; (i) <= (int)(n); (i)++) {
    if (a[i] != b[i]) sm = 0;
    if (i > 1) {
      if (b[i] == b[i - 1])
        asc = dec = 0;
      else if (b[i] > b[i - 1])
        dec = 0;
      else
        asc = 0;
    }
  }
  if (sm) ppt();
  sm = 1;
  for (int(i) = 1; (i) <= (int)(n); (i)++)
    if (a[i] != b[n + 1 - i]) {
      sm = 0;
      break;
    }
  if (sm) {
    addo('R', 1);
    ppt();
  }
  if (asc) {
    for (int i = n; i > 1; i--) b[i] -= b[i - 1];
    addo('P', 1);
  } else if (dec) {
    reverse(b + 1, b + 1 + n);
    addo('R', 1);
  } else
    etn();
  calmore();
}
void fmain(int tid) {
  scanf("%d", &n);
  for (int(i) = 1; (i) <= (int)(n); (i)++) scanf("%lld", a + i);
  for (int(i) = 1; (i) <= (int)(n); (i)++) scanf("%lld", b + i);
  if (n == 1) {
    if (a[1] != b[1]) etn();
    ppt();
  } else if (n == 2)
    cal2();
  else
    calmore();
}
int main() {
  int t = 1;
  for (int(i) = 1; (i) <= (int)(t); (i)++) {
    fmain(i);
  }
  return 0;
}
