#include <bits/stdc++.h>
using namespace std;

int main() {
    int n,m,p,q;
    cin>>n>>m>>p>>q;
    int ans=0,month=1;
    while(n>0){
        ans++;
        if(month>=p&&month<=p+q-1){
            n-=2*m;
        }else{
            n-=m;
        }
        month++;
        if(month==13)month=1;
    }
    cout << ans << endl;
    return 0;
}