#include <bits/stdc++.h>
using namespace std;
inline long long mod(long long n, long long m) {
  long long ret = n % m;
  if (ret < 0) ret += m;
  return ret;
}
long long gcd(long long a, long long b) {
  return (b == 0LL ? a : gcd(b, a % b));
}
long long exp(long long a, long long b, long long m) {
  if (b == 0LL) return 1LL;
  if (b == 1LL) return mod(a, m);
  long long k = mod(exp(a, b / 2, m), m);
  if (b & 1LL) {
    return mod(a * mod(k * k, m), m);
  } else
    return mod(k * k, m);
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int n;
  cin >> n;
  vector<long long> a(n), b(n);
  for (int i = 0; i < n; i++) cin >> a[i];
  for (int i = 0; i < n; i++) cin >> b[i];
  if (n == 1) {
    if (a[0] == b[0]) {
      cout << "SMALL\n0\n";
    } else
      cout << "IMPOSSIBLE"
           << "\n";
    return 0;
  }
  if (n == 2) {
    vector<pair<int, int> > res;
    long long tot = 0;
    while (true) {
      if (min(b[0], b[1]) == 0)
        return cout << "IMPOSSIBLE"
                    << "\n",
               0;
      if (a == b) break;
      if (a[0] == b[1] and a[1] == b[0]) {
        res.push_back(pair<int, int>(1, 0));
        break;
      }
      if (b[0] == b[1]) {
        cout << "IMPOSSIBLE"
             << "\n";
        return 0;
      }
      if (b[0] > b[1]) {
        swap(b[0], b[1]);
        res.push_back(pair<int, int>(1, 0));
      }
      if (a[0] == b[0] and a[1] < b[1] and (b[1] - a[1]) % b[0] == 0) {
        res.push_back(pair<int, int>((b[1] - a[1]) / b[0], 1));
        tot += (b[1] - a[1]) / b[0];
        break;
      }
      if (a[1] == b[0] and (a[0] < b[1] and (b[1] - a[0]) % b[0] == 0)) {
        res.push_back(pair<int, int>((b[1] - a[0]) / b[0], 1));
        res.push_back(pair<int, int>(1, 0));
        tot += (b[1] - a[0]) / b[0];
        break;
      }
      res.push_back(pair<int, int>(b[1] / b[0], 1));
      tot += b[1] / b[0];
      b[1] %= b[0];
    }
    if (tot > 2e5) {
      cout << "BIG"
           << "\n";
      cout << tot << "\n";
      return 0;
    } else {
      cout << "SMALL\n";
      tot = 0;
      for (auto it : res) tot += it.first;
      cout << tot << "\n";
      for (int j = (int)res.size() - 1; j >= 0; j--) {
        auto it = res[j];
        for (int i = 0; i < it.first; i++) {
          if (it.second == 0)
            cout << "R";
          else
            cout << "P";
        }
      }
      cout << "\n";
      return 0;
    }
    return 0;
  }
  vector<int> res;
  while (true) {
    if (a == b) break;
    reverse(a.begin(), a.end());
    if (a == b) {
      res.push_back(0);
      break;
    }
    reverse(a.begin(), a.end());
    bool inc = 1, dec = 1, equal = 0;
    for (int i = 0; i < n - 1; i++) {
      if (b[i + 1] < b[i])
        inc = 0;
      else if (b[i + 1] > b[i])
        dec = 0;
      else
        equal = 1;
    }
    if (!inc and !dec) {
      cout << "IMPOSSIBLE"
           << "\n";
      return 0;
    }
    if (equal) {
      cout << "IMPOSSIBLE"
           << "\n";
      return 0;
    }
    if (dec) {
      res.push_back(0);
      reverse(b.begin(), b.end());
    }
    vector<long long> c(n);
    for (int i = 0; i < n; i++) {
      c[i] = b[i] - (i ? b[i - 1] : 0);
    }
    b = c;
    res.push_back(1);
  }
  if (a == b) {
    int qtd = 0;
    for (auto it : res)
      if (it == 1) qtd++;
    if (qtd > 2e5) {
      cout << "BIG"
           << "\n";
      cout << qtd << "\n";
      return 0;
    } else {
      cout << "SMALL"
           << "\n";
      cout << res.size() << "\n";
      for (int i = (int)res.size() - 1; i >= 0; i--)
        cout << (res[i] == 0 ? "R" : "P");
      cout << "\n";
      return 0;
    }
  }
  cout << "IMPOSSIBLE"
       << "\n";
  return 0;
}
