#include <stdio.h>
#include <stdlib.h>
#include <sstream>
#include <iostream>

using namespace std;

char upcase(char a) {
  if (a>='a' && a<='z') return a+('A'-'a');
  return a;
}

int main() {
  	while (cin) {
	  double years;
	  double debt,salary,interest;
	  cin >> debt >> salary >> years >> interest;
	  if (debt==0 && salary==0 && years==0 && interest==0) return 0;
	  
	  int months=years*12;
	  double interest_pm=interest/1200;
	  double last_debt = debt;
	  while (months>0 && debt>0) {
	    debt *= (1 + interest_pm);
	    debt -= salary;
	    //	    if (last_debt<debt) break;
	    //cout << "month=" << months << " debt=" << debt << endl;
	    months--;
	    last_debt = debt;
	  }
	  
	  if (debt>0) {
	    cout << "NO" << endl;
	  } else {
	    cout << "YES" << endl;
	  }

	}
	return 0;
}