#include <stdio.h>

void StartProgram()
{
    int tMonsterHP, tMonsterAP, aMonsterHP, aMonsterAP;
    //printf("Insert values of Takahashi and Aoki monsters: \n");
    
    scanf("%d %d %d %d",&tMonsterHP, &tMonsterAP, &aMonsterHP, &aMonsterAP);
    
    if(tMonsterHP > 100 || tMonsterAP > 100 || aMonsterHP > 100 || aMonsterAP > 100)
    {
        printf("Wrong input \n");
        printf("\n");
        StartProgram();
    }
    else if (tMonsterHP < 1 || tMonsterAP < 1 || aMonsterHP < 1 || aMonsterAP < 1)
    {
        printf("Wrong input \n");
        printf("\n");
        StartProgram();
    }
    
    while(1)
    {
        aMonsterHP = aMonsterHP - tMonsterAP;
        if(aMonsterHP <=0)
        {
            printf("Yes \n");
            break;
        }
        tMonsterHP = tMonsterHP - aMonsterAP;
        if(tMonsterHP <= 0)
        {
            printf("No \n");
            break;
        }
    }
        
    
    return ;
}

int main(int argc, const char * argv[])
{
    StartProgram();
    
    return 0;
}
