import java.util.Scanner;
public class Main {

	public static void main(String[] args) {
		Scanner t=new Scanner(System.in);
		int a=t.nextInt(), b=t.nextInt(), c=t.nextInt();
		while(a != b && c !=0) {
			b = b +1;
			c = c-1;
			}
		System.out.println(c);
		
	}
	}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz