#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>

long howManyGames(int p, int d, int m, int s) {
    // Return the number of games you can buy
    int k=0,c=0;
    while(k<=s)
    {if(p<=m)
    {
        p=m;
        k=k+p;
    }
     else{
        k=k+p;
        p=p-d;
     }
        c++;
    }
    return c-1;
}

int main() {
    int p; 
    int d; 
    int m; 
    int s; 
    scanf("%i %i %i %i", &p, &d, &m, &s);
    long answer = howManyGames(p, d, m, s);
    printf("%ld\n", answer);
    return 0;
}