import java.util.Scanner;
class Main{
  public static void main(String args[]){
	Scanner scanner=new Scanner(System.in).useDelimiter("\\s");
	int maxAmountofA=scanner.nextInt();
    int currentAmountofA=scanner.nextInt();
    int currentAmountofB=scanner.nextInt();
    if(maxAmountofA-currentAmountofA>=currentAmountofB){
    	System.out.println(0); 
    }else{
    	currentAmountofB-=(maxAmountofA-currentAmountofA);
      	System.out.println(currentAmountofB);
    }
	//int maxAmountOfA=
  }
}
/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