#yuki555

n=int(raw_input())
c,v=map(int,raw_input().split())
dp=[float('inf') for i in xrange(2*n)]
dp[1]=0
for i in xrange(1,n):
 k=dp[i]+c+v
 idx=i
 while idx<n:
  idx+=i
  dp[idx]=min(dp[idx],k)
  k+=v
res=float('inf')
for i in xrange(n,2*n):
 res=min(res,dp[i])
print res