#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll=long long;
using ld=long double;
using vll=vector<ll>;
using pll=pair<ll,ll>;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);

    ll A,B,C,D;
    cin>>A>>B>>C>>D;
    A%=D;B%=D;C%=D;
    cout<<((A*B)%D*C)%D<<endl;
}