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

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl
#define p_yes() p("Yes")
#define p_no() p("No")

const ll mod = 1e9 + 7;
const ll inf = 1e18;

ll fall[13];

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    ll N, M, P, Q;
    cin >> N >> M >> P >> Q;

    FOR(i, 1, 13){
        fall[i] = M;
    }
    FOR(i, P, P+Q){
        fall[i] *= 2;
    }

    ll count = 0;
    ll month = 1;
    for(;;){
        if(month==13) month=1;
        N -= fall[month];
        count++;
        if(N<=0){
            p(count);
            return 0;
        }
        month++;
    }
    
    return 0;
}