import java.util.*;
class Main{
    public static void main(String[] args){
	Scanner stdIn = new Scanner(System.in);
        int A = stdIn.nextInt();
	int B = stdIn.nextInt();
	int C = stdIn.nextInt();
	int o = A-B;
	if(o!=0){
	    C-=o;
	}
	if(C>0){
	    System.out.println(C);
	}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