import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main {
	public static void main(String args[]) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String str[] = br.readLine().split(" ");
		int a = Integer.parseInt(str[0]);
		int b = Integer.parseInt(str[1]);
		int c = Integer.parseInt(str[2]);

		int d = a - b - c;
		if (d < 0) {
			System.out.println(Math.abs(d));
		} else {
			System.out.println(0);
		}
	}
}
/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