#!/usr/bin/env python3

T = 12


def solve(n, m, p, q):
    per_cycle = (T - q) * m + q * 2 * m
    num_cycles, rest_leaves = divmod(n, per_cycle)
    per_months = [m] * (p - 1) + [2 * m] * q + [m] * (T - p - q + 1)
    for idx_month, per_month in enumerate(per_months):
        if rest_leaves <= 0:
            return num_cycles * T + idx_month
        else:
            rest_leaves -= per_month
    raise Exception("Error")


def main():
    n, m, p, q = (int(z) for z in input().split())
    print(solve(n, m, p, q))

if __name__ == '__main__':
    main()