#include<stdio.h>
int main()
{
	long long int n, m, p, q;
	scanf("%lld %lld %lld %lld", &n, &m, &p, &q);
	long long int ans = n / (12 * m + m * q);
	n %= 12 * m + m * q;
	ans *= 12;
	long long int i = 1;
	while (n > 0)
	{
		if (p <= i && i <= p + q - 1)
			n -= 2 * m;
		else
			n -= m;
		ans++;
		i++;
	}
	printf("%lld\n", ans);
	return 0;
}