#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 cost=p;
    int count=1;
    int prev=p;
    while(cost<=s){
        if((prev-d) >= m){
            //printf("prev\n");
            cost=cost+(prev-d);
            prev=prev-d;
            count++;
        }
        else{
           // printf("nprev\n");
            cost=cost+m;
            count++;
        }
        
    }
    if(cost>s)
        return count-1;
    else
        return count;
}

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;
}