#include <bits/stdc++.h>
using namespace std;

using i64 = int64_t;
using u64 = uint64_t;

#define rep(i,n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define ALL(x) (x).begin(),(x).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define SZ(x) ((int)(x).size())
#define PRINT(n) cout << (n) << "\n";

void YESorNO(bool p) {
  cout << (p ? "YES" : "NO") << endl;
  return;
}

void run() {
  u64 a, b, c, d;
  cin >> a >> b >> c >> d;
  cout << (u64)((__int128_t)a * b * c % d) << endl;
  return;
}

int main() {
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  run();
  return 0;
}