n = int(input())
c, v = map(int, input().split())
dp = [float('inf')]*(2*n+1)
dp[1] = 0
for i in range(1, n+1):
    for j in range(i+i, 2*n+1, i):
        dp[j] = min(dp[j], dp[i]+c+v*(j//i-1))
print(min(dp[n:]))