n, a, b = map(int, input().split())
if a <= b:
    ans = (n - 1) * (a - b) - b
else:
    ans = 10**18
q, r = divmod(n, 2)
ans = min(ans, 
          (-a - b) * q - (a - b) * (q - 1 + r) - b * (-1)**(r + 1), 
          -(a - b) * q + (-a - b) * (q - 1 + r) - b * (-1)**r)
print(ans)