import java.util.Scanner; public class No538 { public static void main(String[] args) { Scanner sc = new Scanner(System.in); long b1 = sc.nextLong(); long b2 = sc.nextLong(); long b3 = sc.nextLong(); long rbunbo,rbunshi,d; rbunbo = b2 - b1; rbunshi = b3 - b2; d = b2 - b1 * rbunshi / rbunbo; System.out.println(b3 * rbunshi / rbunbo + d); } }