n,c,v = map(int,open(0).read().split())
ans = INF = 1<<60
dp = [INF]*(n)
dp[1] = 0
for i in range(1,n):
    r = dp[i] + c
    for j in range(i+i,n,i):
        r += v
        dp[j] = min(dp[j],r)
    ans = min(ans,r+v)
print(ans)