## https://yukicoder.me/problems/no/2099


def main():
    T = int(input())
    X, A = map(int, input().split())
    Y, B = map(int, input().split())

    # yが取りうる最小値を取得
    if T >= 0:
        y_min = 0
    else:
        y_min = (- T) // B + (1 if (-T) % B > 0 else 0)

    # 本処理
    min_answer = float("inf")
    t = (T + y_min * B) % A
    cost = y_min

    # 一発目
    xx = T + cost * B
    answer = cost * Y + t
    xx0 = xx - t
    a = xx0 // A
    answer += a * X
    min_answer = min(min_answer, answer)

    first = t 
    cost += 1
    t += B
    t %= A
    while t != first:
        xx = T + cost * B
        answer = cost * Y + t
        xx0 = xx - t
        a = xx0 // A
        answer += a * X
        min_answer = min(min_answer, answer)
        cost += 1
        t += B
        t %= A


    print(min_answer)

    


    



if __name__ == "__main__":
    main()