#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<vector>
#include<string>
#include<utility>
#include<map>
#include<set>
#include<queue>
#include<stack>
#include<functional>
#include<math.h>
#include<random>
#include <bitset>
#include <cassert>
#include <complex>
using namespace std;
#define N (1000000000+7)
//#define N 998244353
#define INF 1e16
typedef long long ll;
typedef pair<int,int> P;
const int inf = 1e8;




int main() {
    int n,m,p,q;
    cin>>n>>m>>p>>q;
    int ans = 0;
    while(true){
        for(int i=1;i<=12;i++){
            ans++;
            if((i>=p)&&(i<=p+q-1))n-=2*m;
            else n-=m;
            if(n<=0){
                cout<<ans<<endl;
                return 0;
            }
        }
    }
}