# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')
from collections import *
from itertools import *
from functools import *
import math,sys
input = sys.stdin.readline


N,A,B = map(int,input().split())
if A < B:
    print((A-B)*N - A)
    exit()

if N%2==0:
    print(-A*(N-1))
else:
    print(-A*(N-1)-B)