import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################[
n, a, b = na()
if b > 2*a:
    print(-b*n + a * (n-1))
else:
    f = (n-1)//2
    print(-a * f*2 + a * (n - 1 - f*2) + b * f - b * (n - f))