d = int(input())
a, b = map(int, input().split())

assert(0 <= d <= 10 ** 4)
assert(0 <= a <= 10 ** 3)
assert(0 <= b <= 10 ** 3)

ans = 10 ** 18

for x in range(d + 1):
    ans = min(ans, x * a + (d - x) * b)

print(ans)