#include<bits/stdc++.h>
#include <iostream>
using namespace std;
#define ll long long int
#define sc(a) scanf("%lld", &a)
#define scs(a) scanf("%s", a)
#define prs(a) printf("%s", a)
#define prsl(a) printf("%s\n", a)
#define pr(a) printf("%lld ", a)
#define prl(a) printf("%lld\n", a)
#define rep(i, a, b) for(i=a; i<b; i++)
#define ren(i, a, b) for(i=a; i>=b; i--)
int main() {
	ll i, p, d, m, s, count=0, sum=0;
    sc(p); sc(d); sc(m); sc(s);
    while(sum<=s){
        if(p>=m){sum+=p;}
        else {sum=sum+m;}
        p=p-d;
        count++;
    }
    pr(count-1);
	return 0;
}