#include<iostream>
#include<algorithm>
using namespace std;
using ll = long long;
int main(){
    ll N,M,P,Q,ans=0;
    ll month[13]={0};
    cin >> N >> M >> P >> Q;
    for(ll i=1;i<P;i++)    month[i]=M;
    for(ll i=P;i<P+Q;i++) month[i]=M*2;
    for(ll i=P+Q;i<=12;i++)    month[i]=M;
    ll s=1;
    while(N>0){
        if(s==13)    s=1;
        N-=month[s];
        s++;
        ans++;
    }
    cout << ans << endl;
    return 0;
}