#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <climits>

#define rep(i, m, n) for(int i=int(m);i<int(n);i++)
#define all(c) begin(c),end(c)

template<typename T1, typename T2>
inline void chmin(T1 &a, T2 b) { if (a > b) a = b; }

template<typename T1, typename T2>
inline void chmax(T1 &a, T2 b) { if (a < b) a = b; }

//改造
typedef long long int ll;
using namespace std;
#define INF (1 << 30) - 1
#define INFl (ll)5e15
#define DEBUG 0 //デバッグする時1にしてね
#define dump(x)  cerr << #x << " = " << (x) << endl
#define MOD 1000000007


//ここから編集する


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

    ll N, M, P, Q;

    cin >> N >> M >> P >> Q;

    ll year = M * 12 + Q * M;

    ll ans = N / year * 12;
    N -= N / year * year;

    if (N == 0) {
        cout << ans << endl;
        return 0;
    }
    for (int i = 1; i <= 12; ++i) {
        ans++;
        if (i >= P && i <=P + Q-1) {
            N -= 2 * M;
        } else {
            N -= M;
        }
        if(N <= 0) break;
    }
    cout << ans << endl;


    return 0;
}