c#include <bits/stdc++.h> using namespace std; int main(){ cin.tie(NULL); cout.tie(NULL); ios_base::sync_with_stdio(false); int A, B, C, M; cin >> A >> B >> C >> M; int ans = 0; int sum = 0; for(int t = 0; t < 24; t++){ if(sum + A > M){ sum -= C; sum = max(sum, 0); }else{ ans += B; sum += A; } } cout << ans << "\n"; return 0; }