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



int main() {
    int p; 
    int d; 
    int m; 
    int s; 
    scanf("%d %d %d %d", &p, &d, &m, &s);
    int n=0;
    int cost=0;
    
    while(1)
    {
        if(cost<=s){
        if((p-(d*n))>=m)
        cost=cost+p-(d*n);
        else cost=cost+m;
        if(cost<=s) n++;}
        else break;
    }
    //n--;
        printf("%d\n",n);
    
    return 0;
}