#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
    if(p<0||d<0||m<0||s<0) return 0;
   int i,count=1,sum=0,flag=0,k;
    while(1){
        sum=sum+p;
        p=p-d;
        k=p;
        count++;
        if((k-m)%2==0){
            sum=sum+m;
            //count++;
        }
        if(sum>s) break;
    }
    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;
}