import Data.Ratio

main = do
 [b1,b2,b3] <- map read . words <$> getLine
 print (ngs b1 b2 b3)

ngs b1 b2 b3 = numerator (r * (fromIntegral b3) + d)
 where (r,d) = simeq b1 b2 b2 b3

simeq x y z w = (r,d)
 where
  r = (y-w) % (x-z)
  d = (fromIntegral w) - r * (fromIntegral z)