import numpy as np

N = int(input())
C, V = map(int, input().split())
MAX = 10 ** 8

dp = np.full(2 * N, MAX)
dp[1] = 0
for i in range(1, N):
    np.minimum(dp[i * 2::i], dp[i] + C + V * np.arange(1, (2 * N - 1) // i), out=dp[i * 2::i])
print(dp[N:].min())