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