#include <bits/stdc++.h>

template<typename T>
class Array {
public:
  T* p; int size; int seek;
  Array(int N) { p = new T[N]; size = N; seek = 0; }
  Array(int N, T x) { p = new T[N]; for(int i = 0; i < N; ++i) p[i] = x; size = N; seek = 0; }
  const T& operator() (int i) const { return p[i]; }
};
template<typename T> inline Array<T> update(Array<T>& xs, int i, const T& x) { Array<T> res = xs; res.p[i] = x; xs.p = nullptr; return res; }
template<typename T, typename U> inline T foldl1(U f, Array<T>& xs) { T res = xs(0); for(int i = 1; i < xs.size; ++i) { res = f(res, xs(i)); } return res; }
template<typename T> T add(const T& x, const T& y) { return x + y; }

int main() {
  long a; scanf("%ld", &a);
  long b; scanf("%ld", &b);
  long c; scanf("%ld", &c);
  long d; scanf("%ld", &d);
  long res = a * b % d * c % d;
  printf("%ld\n", res);
  
  return 0;
}