def f_cost(d, a, b):
    cost_list = []
    for x in range(d + 1):
        cost = x * a + (d - x) * b
        cost_list.append(cost)
    return min(cost_list)

if __name__ == '__main__':
    d = input()
    d = int(d)
    a, b = map(int, input().split())
    result = f_cost(d, a, b)
    print(result)