#!python
# -*- coding: utf-8 -*-


def main():
    N, M, P, Q = map(int, input().split())
    y = Q * 2 * M + (12 - Q) * M
    ans = N // y * 12
    r = N % y
    for m in range(1, 13):
        ans += 1
        if P <= m < P + Q:
            r -= 2 * M
        else:
            r -= M
        if r <= 0:
            break
    print(ans)


if __name__ == '__main__':
    main()