/*
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 * and open the template in the editor.
 */

/**
 *
 * @author cteam042
 */
import java.util.Scanner;
import java.math.BigDecimal;

public class mortgage {

    public static class G
    {
        public static double eps = 0.000000001;
    }
    
    static Scanner scanner;
    
    public static void main(String[] args)
    {
        scanner = new Scanner(System.in);
        while(1==1)
        {
            String line = scanner.nextLine();
            if (line.equals("0 0 0 0"))
                break;
            String[] parts = line.split(" ");
            int x = Integer.parseInt(parts[0]);
            int y = Integer.parseInt(parts[1]);
            int months = Integer.parseInt(parts[2]) * 12;
            double rate = Double.parseDouble(parts[3]) / 1200;
            
            if (x*rate >= y + G.eps)
            {
                System.out.println("NO");
                continue;
            }
            
            if (x*rate <= 0 + G.eps)
            {
                 if (months*y >= x + G.eps)
                 {
                         System.out.println("YES");
                         continue;
                 }
            }
            
            if (months*y <= x)
            {
                System.out.println("NO");
                continue;
            }
            
            boolean possible = false;
            BigDecimal X = BigDecimal.valueOf(x);
            BigDecimal RATE = BigDecimal.valueOf(rate);
            BigDecimal Y = BigDecimal.valueOf(y);
            BigDecimal NULA = BigDecimal.valueOf(G.eps);
            
            for (int i = 0; i < months; i++)
            {
                X = X.add(X.multiply(RATE));
                X = X.subtract(Y);
                
                if (X.compareTo(NULA) < 0)
                {
                    possible = true;
                    break;
                }
            }
            
            if(possible)
                    System.out.println("YES");
            else
                System.out.println("NO");
        }
    }
    
}