import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;

class Main {

	class BIT {
		int n;
		long[] v;

		public BIT(int n_) {
			n = n_;
			v = new long[n + 1];
		}

		void add(int k, int val) {
			while (k <= n) {
				v[k] += val;
				k += k & -k;
			}
		}

		long sum(int k) {
			long ret = 0;
			while (k >= 1) {
				ret += v[k];
				k -= k & -k;
			}
			return ret;
		}

		long sum(int l, int r) {
			return sum(r - 1) - sum(l - 1);
		}
	}

	final long MOD = (long) 1e9 + 7;

	void run() {
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		int M = sc.nextInt();
		int P = sc.nextInt();
		int Q = sc.nextInt();
		PrintWriter pw = new PrintWriter(System.out);
		// M枚ずつ葉を落とす
		// [P,P+Q) 2*M枚ずつ葉を落とす
		long ans = 0;
		ans += N / (M * (12 - Q) + 2 * M * Q) * 12;
		N = N % (M * (12 - Q) + 2 * M * Q);
		if (N == 0) {
			System.out.println(ans);
			return;
		}
		for (int i = 1; i <= 12; ++i) {
			ans++;
			if (P <= i && i < P + Q) {
				N -= 2 * M;
			} else {
				N -= M;
			}
			if (N <= 0) {
				System.out.println(ans);
				return;
			}
		}
		pw.close();
	}

	long inv(long a) {
		return pow(a, MOD - 2);
	}

	long pow(long a, long n) {
		long ret = 1;
		for (; n > 0; n >>= 1, a = a * a % MOD) {
			if (n % 2 == 1)
				ret = ret * a % MOD;
		}
		return ret;
	}

	class SegmentTree {
		int n;
		int[] sum;

		public SegmentTree(int n_) {
			n = 1;
			while (n < n_) {
				n *= 2;
			}
			sum = new int[2 * n - 1];
		}

		void add(int k) {
			k += n - 1;
			++sum[k];
			while (k > 0) {
				k = (k - 1) / 2;
				sum[k] = sum[2 * k + 1] + sum[2 * k + 2];
			}
		}

		int query(int a, int b) {
			return query(0, n, a, b, 0);
		}

		int query(int l, int r, int a, int b, int k) {
			if (r <= a || b <= l)
				return 0;
			else if (a <= l && r <= b)
				return sum[k];
			else {
				return query(l, (l + r) / 2, a, b, 2 * k + 1) + query((l + r) / 2, r, a, b, 2 * k + 2);
			}
		}
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}

	public static void main(String[] args) throws FileNotFoundException {
		new Main().run();
	}
}