#include <iostream>
#include <vector>
#include <map>
using namespace std;
template<class T> bool maxPointer(T& a, T b) { if (a < b) {a = b;return true;}return false;}
template<class T> int maxReturn(T a, T b) {if (a > b) {return a;} else {return b;}}
template<class T> bool minPointer(T& a, T b) {if (a < b) {a = b;return true;}return false;}


int main(void){
    int N,M,P,Q,month = 1,res=0,windBounus=1;
    cin >> N >> M >> P >> Q;
    
    for(; N > 0; res++) {
        if (month == P+Q) windBounus = 1;
        if (month == 13) month = 1;
    	if (month == P) windBounus = 2;
    	

    	N -= M * windBounus;
    	month++;
    }
    
    cout << res << endl;
}