/*****************/
/*

Sharma Ji Ka Ladka
MNNIT Allahabad

*/
/*****************/

#include <bits/stdc++.h>
using namespace std;

#define For(i, a, b) for (int i = a; i < b; i++)
#define Forl(i, size) for (int i = 0; i < size; i++)
#define Forr(i, size) for (int i = size - 1; i >= 0; i--)
#define ForR(i, a, b) for (int i = a; i >= b; i--)
#define s(n) scanf("%d", &n)
#define p(n) printf("%d\n", n)
#define ps(n) printf("%s\n", n)
#define sd(n) \
    int n;    \
    scanf("%d", &n)
#define sl(n)        \
    long long int n; \
    scanf("%lld", &n)
#define pb(n) push_back(n)
#define clr(a) memset(a, 0, sizeof(a))
#define all(c) (c).begin(), (c).end()
#define len length()
#define size size()
#define mp(a, b) make_pair(a, b)
#define fi first
#define se second
typedef unsigned long long ull;
#define ret return 0;
#define PI 3.14159265
#define snuke(c, itr) for (__typeof((c).begin()) itr = (c).begin(); itr != (c).end(); itr++)
#define boost                         \
    ios_base::sync_with_stdio(false); \
    cin.tie(NULL);                    \
    cout.tie(NULL);
const long long Mod = 1e9 + 7;
// string a,b,s,c,d;

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<string> vst;
typedef vector<bool> vb;
typedef pair<int, int> pii;
typedef long long ll;
typedef long double ld;
ll sum = 0, ans = 0, res = 0;
int i, j, k;

bool sortbysec(const pair<int, int> &a,
               const pair<int, int> &b)
{
    if (a.se == b.se)
        return (a.fi < b.fi);

    return (a.se < b.se);
}

// IS PRIME FUNCTION STARTS

bool isPrime(ll num)
{
    bool flag = true;
    if (num == 1)
        return false;
    for (int i = 2; i <= sqrt(num); i++)
    {
        if (num % i == 0)
        {
            flag = false;
            break;
        }
    }
    return flag;
}

//IS PRIME FUNCTION ENDS

//**Array Sum Function**

ll findSum(ll a[], int l, int r)
{
    ll sum = 0;
    For(i, l, r)
    {
        sum += a[i];
    }
    return sum;
}

//**Array Sum Function Ends**

//Prime Factors Of A Number

vector<pair<int, int>> vec1; //Prime Factors along with their exponents
void primeFactors(ll n)
{
    int c1 = 0;
    // Print the number of 2s that divide n
    while (n % 2 == 0)
    {
        // printf("%d ", 2);
        n = n / 2;
        c1++;
    }
    if (c1)
        vec1.pb(mp(2, c1));
    c1 = 0;
    // n must be odd at this point. So we can skip
    // one element (Note i = i +2)
    for (int i = 3; i <= sqrt(n); i = i + 2)
    {
        c1 = 0;
        // While i divides n, print i and divide n
        while (n % i == 0)
        {
            // printf("%d ", i);

            n = n / i;
            c1++;
        }
        if (c1)
            vec1.pb(mp(i, c1));
    }
    c1 = 0;
    // This condition is to handle the case when n
    // is a prime number greater than 2
    if (n > 2)
        vec1.pb(mp(n, 1));
}

//Ends

//*** Power Function Starts
ll power(int x, unsigned int y)
{
    int temp;
    if (y == 0)
        return 1;
    temp = power(x, y / 2);
    if (y % 2 == 0)
        return temp * temp;
    else
        return x * temp * temp;
}
//*** Power function ends

//nCr function starts

ull nCr(ll n, ll r)
{
    ull p = 1;
    ull k = 1;
    if (n - r < r)
        r = n - r;

    if (r != 0)
    {
        while (r)
        {
            p *= n;
            k *= r;
            ll m = __gcd(p, k);
            p /= m;
            k /= m; //Simplifying
            n--;
            r--;
        }
    }
    else
        p = 1;

    return p;
}

//nCr function ends

// ** LCM of two numbers
ll lcm(ll a, ll b)
{
    return a / __gcd(a, b) * b;
}
//** Ends //

//** Count Set Bits Functon

unsigned int countBits(ll n, int specify)
{
    unsigned int count = 0, total = 0;
    if (n == 0)
    {
        if (specify == 1)
            return 0;
        else
            return 1;
    }
    while (n)
    {
        total += 1;
        count += n & 1;
        n >>= 1;
    }
    if (specify == 1)
        return count;
    else
        return (total - count);
}

//** Ends //

//Array Scanner starts

void scar(ll a[], int n)
{
    for (int i = 0; i < n; i++)
    {
        cin >> a[i];
    }
}

//Array Scanner ends
//  long long findTargetSumWays(vector<int>& vec, int S) {

//         long long sum=0;
//         for(int i=0;i<vec.size;i++)
//         {
//             sum+=vec[i];
//         }
//         // cout<<sum<<endl;
//         if(sum<S||(sum+S)%2!=0)return 0;
//         long long s1=(sum+S)/2;

//         long long dp[vec.size+10][s1+10]={0};
//         for(int j=0;j<s1+1;j++)
//         {
//             dp[0][j]=0;
//         }
//         for(int i=0;i<vec.size+1;i++)
//         {
//             dp[i][0]=1;
//         }
//         for(i=1;i<vec.size+1;i++)
//         {
//             For(j,0,s1+1)
//             {if(j>=vec[i-1])
//                 dp[i][j]=dp[i-1][j]+dp[i-1][j-vec[i-1]];
//                 else
//                 {
//                     dp[i][j]=dp[i-1][j];
//                 }

//             }
//         }
//         return dp[vec.size][s1];

//     }

signed main()
{
    // boost
    string aux1, aux2, aux3;

    int T = 1;
    // cin>>T;
    Forl(ZA, T)
    {
        int f = 0, fl1 = 0, fl2 = 0, c1 = 0, c2 = 0, cont = 0, cnt = 0, c3 = 0, auxi = 0, auxj = 0;
        ll mi = INT_MAX;
        ll ma = INT_MIN, sol = 0;
    //  int n;cin>>n;
    //  string s[n];
    //  set<string> S;
    //  For(i,0,n)


    //  {cin>>s[i];S.insert(s[i]);}
    //  cout<<S.size<<endl;
    
    int a,b,c,d;
    cin>>a>>b>>c>>d;
    // cout << ceil((double)c / (double)b) << "  " << ceil((double)a / (double)d)<<endl;
     if (ceil((double)c / (double)b) > ceil((double)a / (double)d))
    {
        cout<<"No\n";
    }
    // __enable_shared_from_this_base
    else
    {
        cout<<"Yes\n";
    }
         }
    return 0;
}


Measured memory_bytes: 3724