#!/usr/bin/python3
from fractions import Fraction

a, b, c = map(int, input().split())
assert -10**5 <= a <= 10**5
assert -10**5 <= b <= 10**5
assert -10**5 <= c <= 10**5
assert a != b

r = Fraction(c-b, b-a)
#import sys
#print(r, file=sys.stderr)
assert r != 0
d1 = b - r * a
d2 = c - r * b
assert d1 == d2
res = r * c + d1
print(res)