#include <iostream>
#include <numeric>
#include <cmath>
#include <limits>
#include <stdio.h>
#include <iomanip>
#include <string> // string, to_string, stoi
#include <vector> // vector
#include <algorithm> // min, max, swap, sort, reverse, lower_bound, upper_bound
#include <utility> // pair, make_pair
#include <tuple> // tuple, make_tuple
#include <cstdint> // int64_t, int*_t
#include <cstdio> // printf
#include <map> // map
#include <queue> // queue, priority_queue
#include <set> // set
#include <stack> // stack
#include <deque> // deque
#include <unordered_map> // unordered_map
#include <unordered_set> // unordered_set
#include <bitset> // bitset
#include <cctype> // isupper, islower, isdigit, toupper, tolower
using namespace std;
using ll = long long;
#define all(A) A.begin(),A.end()
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
ll Max(ll(a), ll(b), ll(c)) {
    return max(max(a, b), c);
}
ll Min(ll(a), ll(b), ll(c)) {
    return min(min(a, b), c);
}



ll Q[4000002];

ll modPow(ll a, ll n, ll p) {
    if (n == 0) return 1;
    if (n == 1) return a % p;
    if (n % 2 == 1) return (a * modPow(a, n - 1, p)) % p;
    long long t = modPow(a, n / 2, p);
    return (t * t) % p;
}
ll Xor(ll a, ll b) {
    ll A = a, B = b;
    ll C = 0;
    ll k = 1;
    while (A > 0 || B > 0) {
        if (A % 2 != B % 2) {
            C += k;
        }
        k *= 2;
        A /= 2;
        B /= 2;

    }
    return C;
}
vector<ll> fact, factinv, inv;
ll mod = 998244353;
void prenCkModp(ll n) {
    fact.resize(n + 5);
    factinv.resize(n + 5);
    inv.resize(n + 5);
    fact.at(0) = fact.at(1) = 1;
    factinv.at(0) = factinv.at(1) = 1;
    inv.at(1) = 1;
    for (ll i = 2; i < n + 5; i++) {
        fact.at(i) = (fact.at(i - 1) * i) % mod;
        inv.at(i) = mod - (inv.at(mod % i) * (mod / i)) % mod;
        factinv.at(i) = (factinv.at(i - 1) * inv.at(i)) % mod;
    }

}
ll nCk(ll n, ll k) {
    return fact.at(n) * (factinv.at(k) * factinv.at(n - k) % mod) % mod;
}
ll dx[4] = { -1,0,1,0 };
ll dy[4] = { 0,-1,0,1 };
ll stll(string S, ll mod) {
    ll n = 0;
    ll k = 1;
    rep(i, S.size()) {
        n += (k * ll(S[S.size() - i - 1] - '0'));
        k *= 10;
        k %= mod;
        n %= mod;
    }
    return n;
}
ll gcd(ll(a), ll(b)) {
    ll c = a;
    while (a % b != 0) {
        c = a % b;
        a = b;
        b = c;
    }
    return b;
}

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