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

int howManyGames(int p, int d, int m, int s) {
    // Return the number of games you can buy
    int c=0,x=0;
    lop:
    if(x<=s)
    {c++;
      //printf("\n%d",x);
        x=x+p;
    
        if(p-d<=m){p=m;}
        else{
            p=p-d;
        }
        goto lop;
    }
    
    return c-1;
}

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