#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <numeric>
#include <string>
#include <cstdio>
#include <cstring>
#include <queue>
#include <stack>
#include <set>
#include <cmath>
#include <bitset>

typedef long long ll;
typedef unsigned long long ull;
using namespace std;

#define FALSE printf("false\n");
#define TRUE printf("true\n");
#define all(x) (x).begin(),(x).end()
#define rep(i,n) for(int i = 0;(i) < ((int)(n));++(i))
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
#define test(a) cout<<"line:"<<__LINE__<<"["<<(#a)<<": "<<(a)<<"]"<<endl

const int INF = 1e9+7;
const ll INFL = 9*1e18;

// const int dx[4] = { 1, 0, -1, 0 };
// const int dy[4] = { 0, 1, 0, -1 };

const int dx[8] = {1, 1, 0,-1,-1,-1, 0, 1};
const int dy[8] = {0, 1, 1, 1, 0,-1,-1,-1};

#define SUM(vec) accumulate(all(vec),0LL) // 配列の中身を全部足す
template<typename T>void print(T&& x){cout<<x<<endl;}// 改行付き出力
ll inline digit(ll num){int tmp = 0;while(num){tmp++;num/=10;}return tmp;} // 桁数
template<typename T>inline T digitSum(T num){T sum = 0;while(num){sum+=num%10;num/=10;}return sum;} // 各桁の和
template<typename T>inline T gcd(T a,T b){if(b == 0)return a;return gcd(b,a%b);} // 最大公約数
template<typename T>inline T lcm(T a, T b){T g = gcd(a,b);return a/g*b;} // 最小公倍数
template<typename T>inline T power(T a,T b){T tmp=1;rep(i,b){tmp*=a;}return tmp;} // 累乗
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }
int ctoi(char c){return c-'0';}

// TODO: write
int main() {
  int a,b,c,d;cin>>a>>b>>c>>d;
  int cnt = 0;
  while(a > 0 && c > 0){
    if(cnt%2 == 0)c -= b;
    else a -= d;
    cnt++;
  }
  if(cnt%2)print("Yes");
  else print("No");
  return 0; 
}
