import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ


		Scanner sc = new Scanner(System.in);

		//入力表示
		int A=sc.nextInt();
		int B=sc.nextInt();
		int C=sc.nextInt();
		
		int use=Math.min(C, A-B);
		
		if(A-B > C) {
			System.out.println(0);
		}else {
			System.out.println(C-use);
			
		}
	}

}
/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