#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<(int)(n);i++)
using namespace std;
using ll = long long ;
using P = pair<int,int> ;
using pll = pair<long long,long long>;
constexpr int INF = 1e9;
constexpr long long LINF = 1e17;
constexpr int MOD = 1000000007;
constexpr double PI = 3.14159265358979323846;

int main(){
    ll a,b,c,d;
    cin >> a >> b >> c >> d;
    a%=d;b%=d;c%=d;
    cout << (((a*b)%d)*c)%d << endl;
    return 0;
}