N = int(input())
C, V = map(int, input().split())
inf = 10**18
dp = [inf] * (2 * N + 1)
dp[1] = 0

for i in range(1, N):
    x = i + i
    cost = C + V
    while True:
        dp[x] = min(dp[x], dp[i] + cost)
        if x > N:
            break
        x += i
        cost += V

ans = inf
for i in range(N, 2 * N + 1):
    ans = min(ans, dp[i])

print(ans)