#include <bits/stdc++.h>
using namespace std;
const int N = 2e5 + 10;
int n;
long long a[N], b[N];
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) scanf("%lld", &a[i]);
  for (int i = 1; i <= n; i++) scanf("%lld", &b[i]);
  vector<char> ans;
  if (n == 1 && a[1] != b[1]) {
    puts("IMPOSSIBLE");
    return 0;
  } else if (n == 1 && a[1] == b[1]) {
    puts("SMALL");
    puts("0");
    return 0;
  }
  if (n == 2) {
    long long a0 = a[1], a1 = a[2], b0 = b[1], b1 = b[2];
    long long cnt = 0;
    if (a0 > a1) swap(a0, a1);
    while (1) {
      if (b0 == a0 && b1 == a1) {
        break;
      }
      if (b0 <= b1) {
        if (b0 < a0 || b1 < a1) {
          puts("IMPOSSIBLE");
          return 0;
        }
        if (b0 == a0) {
          long long v = max(1ll, (b1 - a1) / b0);
          cnt += v;
          b1 -= v * b0;
        } else {
          long long v = b1 / b0;
          cnt += v;
          b1 -= v * b0;
        }
      } else {
        swap(b0, b1);
      }
    }
    if (cnt > 200000) {
      puts("BIG");
      printf("%lld\n", cnt);
      return 0;
    }
  }
  int cnt = 0;
  while (1) {
    bool sig = 1, sig1 = 1;
    bool the_same = (a[1] == b[1]), re_same = (a[1] == b[n]);
    for (int i = 2; i <= n; i++)
      sig &= (b[i - 1] < b[i]), sig1 &= (b[i - 1] > b[i]),
          the_same &= (b[i] == a[i]), re_same &= (a[i] == b[n - i + 1]);
    if (the_same) break;
    if (re_same) {
      ans.push_back('R');
      break;
    }
    if (!sig && !sig1) {
      puts("IMPOSSIBLE");
      return 0;
    }
    if (sig) {
      if (max(a[1], a[n]) > max(b[1], b[n]) ||
          min(a[n], a[1]) > min(b[n], b[1])) {
        puts("IMPOSSIBLE");
        return 0;
      }
      for (int i = n; i >= 2; i--) b[i] -= b[i - 1];
      ans.push_back('P');
      cnt++;
    } else {
      reverse(b + 1, b + n + 1);
      ans.push_back('R');
    }
  }
  if (cnt > 200000) {
    puts("BIG");
    printf("%d\n", cnt);
  } else {
    puts("SMALL");
    printf("%d\n", (int)ans.size());
    reverse(ans.begin(), ans.end());
    for (auto u : ans) printf("%c", u);
  }
  return 0;
}
