#include "bits/stdc++.h"
#ifndef err
#undef assert
#define assert(ok) if (!(ok)) exit(1);
#define err(...)(void)0
#endif
using namespace std;
#define all(a)(a).begin(),(a).end()
#define repa(i,a,size)for(int i=(a),_l##i=(size);i<_l##i;i++)
#define rep(i,size)repa(i,0,size)
#define rrepa(i,a,size)for(int i=(size)-1;i>=a;i--)
#define rrep(i,size)rrepa(i,0,size)
template<class T>struct It : T { It(T t) { (T&)*this = t; }int i = 0; };
#define range(o,a)for(It<decltype(begin(a))>o=begin(a);o!=end(a);o.i++,o++)
typedef int64_t ll;
typedef uint64_t ull;
void Calc();

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0); cin.exceptions(istream::failbit | istream::badbit);
  cout << fixed << setprecision(15); Calc(); cout.flush(); return 0;
}
template<class T, int n> int size(T(&a)[n]) { return n; }
template<class T> int size(T &a) { return a.size(); }
template<class A>void amax(A&a, A b) { a = max(a, b); }
template<class A>void amin(A&a, A b) { a = min(a, b); }
struct Scanner {
  template<class A>A Next() { A a; cin >> a; return a; }
  template<class A = int>vector<A>Array(int n) { vector<A>a(n); for (A&i : a) cin >> i; return a; }
  string Line() { string s; getline(cin, s); return s; }
  template<class A>Scanner&operator,(A&a) { a = Next<A>(); return *this; }
  template<class A>operator A() { return Next<A>(); }
}in;

/*---------------------------------------------------------------------*/
void Calc() {
  ll a, b, c, d;
  in, a, b, c, d;
  cout << ((a * b) % d)*c % d << endl;
}