#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<ll> vll;
typedef vector<int> vi;
typedef vector<vector<int>> vvi;
typedef vector<vector<ll>> vvll;
const ll inf = 1e16;
const ll md = 1000000007;

int main() {
  ll a,b,c,d;
  cin>>a>>b>>c>>d;
  a%=d;
  b%=d;
  c%=d;
  a=a*b%d;
  a=a*c%d;
  cout<<a<<endl;
}