#include <bits/stdc++.h>
#include <stdarg.h>
#include <assert.h>
#include <ctype.h>
#include <boost/iostreams/filtering_stream.hpp>
#include <boost/iostreams/filter/gzip.hpp>
#include <boost/iostreams/device/file_descriptor.hpp>

using namespace std;
typedef long long int lli;
typedef vector<int> iv;
typedef vector<bool> bv;
typedef vector<string> sv;
typedef vector<long long int> llv;
typedef vector<double> dv;

#define sor_(vec) sort(vec.begin(),vec.end())
#define rev_(vec) reverse(vec.begin(),vec.end())
#define rep(i,n) for(int i=0;i<static_cast<int>(n);i++)
#define reps(i,n,s) for(int i=static_cast<int>(s);i<static_cast<int>(n);i++)
#define isposi(num) if(num>0)
const long long mod = 1000000007;

template<typename TypeInt>
std::string Itoa(const TypeInt v, int base)
{
    static const char table[] = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
    string ret;
    static numeric_limits<TypeInt> t;
    TypeInt n = v;
    if (t.is_signed) {
        if (v < 0) n *= -1;
    }

    while (n >= base) {
        ret += table[n%base];
        n /= base;
    }
    ret += table[n];
    if (t.is_signed) {
        if (v < 0 && base == 10) ret += '-';
    }
    std::reverse(ret.begin(), ret.end());

    return ret;
}

int upf(double num){
    if(num-(int)num>0)return (int)num+1;
    else return num;
}

void printm(char const *format,...){
    va_list arguments;
    va_start(arguments,format);
    unsigned index=0;
    while (format[index]!='\0') {
        if(format[index]=='%'){
            index++;
            if(format[index]=='d')printf("%d",va_arg(arguments, int));
            else if(format[index]=='c')printf("%c",va_arg(arguments, int));
            else if(format[index]=='x')printf("%x",va_arg(arguments,int));
            else if(format[index]=='o')printf("%o",va_arg(arguments,int));
            else if(format[index]=='f')printf("%f",va_arg(arguments, double));
            else if(format[index]=='s')printf("%s",va_arg(arguments, char const *));
            else if(format[index]=='p')printf("%p",va_arg(arguments,void*));
            else if(format[index]=='y')printf("Yes");
            else if(format[index]=='n')printf("No");
            else if(format[index]=='%')printf("%%");
            else assert(!"Unknown format with %.");
        }
        else printf("%c",format[index]);
        index++;
    }
    va_end(arguments);
    return;
}

struct Chara{
    int hp;
    int sp;
};

int main(void){
    cin.tie(0);
    ios::sync_with_stdio(false);
    Chara taka,ao;
    std::cin>>taka.hp>>taka.sp>>ao.hp>>ao.sp;
    if(upf((double)taka.hp/(double)ao.sp)>=upf((double)ao.hp/(double)taka.sp))printm("Yes");
    else printm("No");
    return 0;
}
