#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) {
    int count=0;
    int temp=p;
    while(s>0)
    {
        
        s=s-temp;
        if(temp-d>=m)
            p-=d;
        
        else{
        p=m;    
        }
        //printf("%d\n",p);
       temp=p;
        
        if(s>=0)
            count++;
        
    }
    return count;
    // Return the number of games you can buy
}

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;
}