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

if T < 0:
    required_b = (-T + B - 1) // B
    cost = T + required_b * (Y + B)
    print(cost)
else:
    initial_cost = T
    a_floor = T // A
    a_candidates = [0, a_floor, a_floor + 1, a_floor + 2]
    min_cost = initial_cost

    for a in a_candidates:
        if a < 0:
            continue
        if a * A > T:
            D = a * A - T
            b = (D + B - 1) // B
        else:
            b = 0
        current_cost = T + a * (X - A) + b * (Y + B)
        if current_cost < min_cost:
            min_cost = current_cost

    print(min_cost)