N=int(input())
line=input().split()
C=int(line[0])
V=int(line[1])
dp=[2000000000 for i in range(2*N-1)]
dp[1]=0
for i in range(1,N):
    t=dp[i]+C
    index=i
    while index<N :
        index+=i
        t+=V
        dp[index]=min(dp[index],t)
ans=2000000000
for i in range(N,2*N-1):
    ans=min(ans,dp[i])
print(ans)