#include <bits/stdc++.h>
#define rep(i,n) for(int i=0;i<n;i++)
using namespace std;
using ll =  long long ;
using P = pair<int,int> ;
const int INF = 1e9;
const int MOD = 1000000007;

int main(){
    int n,m,p,q;
    cin >> n >> m >> p >> q;
    int ans = n/((q+12)*m);
    n %= ((q+12)*m);
    ans *= 12;
    int cnt = 0;
    if(n==0){
        cout << ans << endl;
        return 0;
    }
    for(int i=1;i<=12;i++){
        n -= m;
        if(p <= i && i < p+q) n -= m;
        if(n <= 0){
            cnt = i;
            break;
        }
    }
    ans += cnt;
    cout  << ans << endl;
    return 0;
}