#include <bits/stdc++.h>
typedef long long ll;
#define INF 1000000000
#define MOD 1000000007
using namespace std;
int main(void){
    ll a,b,c,d;
    cin>>a>>b>>c>>d;
    a%=d;
    b%=d;
    c%=d;
    ll ans;
    ans=(((a*b)%d)*c)%d;
    cout<<ans<<endl;
}