import java.util.Scanner;

public class Main{
	public static void main(String args[]){
		Scanner scan = new Scanner(System.in);
		int capacityOfA = scan.nextInt();
		int waterInA = scan.nextInt();
		int waterInB= scan.nextInt();
		int printNum = waterInB - (capacityOfA - waterInA);
		if(printNum < 0){
			printNum = 0;
		}
		System.out.println(printNum);
	}
}
/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