#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <memory>
#include <numeric>
#include <set>
#include <stack>
#include <string>
#include <vector>
#include <functional>

#define rep(i,a,b) for(int i=(a);i<(b);++i)
#define MOD 1000000007
#define int long long
using ll = long long;
using namespace std;
const int INF = 1LL << 50;
using P = pair<int, int>;

template <class T>
bool chmin(T &a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    else {
        return false;
    }
}
template <class T>
bool chmax(T &a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    else {
        return false;
    }
}
struct Setup {
    Setup() {
        cin.tie(0);
        ios::sync_with_stdio(false);
        cout << fixed << setprecision(20);
    }
} SETUP;

const int nax = 1e7;
vector<int> dp(nax, 0);

void init(int mod) {
    dp[1] = 1;
    rep(i, 2, nax) {
        dp[i] = (dp[i - 1] + dp[i - 2]) % mod;
    }
}
signed main() {
    int n, m, p, q; cin >> n >> m >> p >> q;
    int ans = 0;
    while (n > 0) {
        bool cc = true;
        rep(i, 1, 13) {
            if (p <= i && i <= q) {
                n -= m * 2;
            }
            else {
                n -= m;
            }
            ans++;
            if (n <= 0) {
                cc = false;
                break;
            }
        }
        if (!cc) break;
    }
    cout << ans << endl;
}