package yukicoder; import java.util.Scanner; public class No538 { public static void main(String[] args) { Scanner sc = new Scanner(System.in); int[] b = {sc.nextInt(), sc.nextInt(), sc.nextInt()}; double r, d, keisu; keisu = 1.0 / (b[1] - b[0]); r = keisu * b[2] + -keisu * b[1]; d = keisu * -b[0] * b[2] + keisu * b[1] * b[1]; System.out.println((int)(r * b[2] + d)); } }