Problem:
Score : 100 points

Problem Statement

We have two bottles for holding water.

Bottle 1 can hold up to A milliliters of water, and now it contains B milliliters of water.

Bottle 2 contains C milliliters of water.

We will transfer water from Bottle 2 to Bottle 1 as much as possible.

How much amount of water will remain in Bottle 2?

Constraints

All values in input are integers.

1 \leq B \leq A \leq 20

1 \leq C \leq 20

Input

Input is given from Standard Input in the following format:

A B C

Output

Print the integer representing the amount of water, in milliliters, that will remain in Bottle 2.

Sample Input 1

6 4 3

Sample Output 1

1

We will transfer two milliliters of water from Bottle 2 to Bottle 1, and one milliliter of water will remain in Bottle 2.

Sample Input 2

8 3 9

Sample Output 2

4

Sample Input 3

12 3 7

Sample Output 3

0

Solution in Rust (1.15.1) (judge verdict: Accepted)

use std::io::Read;
fn main() {
    let (a,b,c) = {
        let inputstr = {
            let mut inputstr = String::new();
            std::io::stdin().read_to_string(&mut inputstr).unwrap();
            inputstr
        };
        let mut inputiter = inputstr.split_whitespace();
        let a =  inputiter.next().unwrap().parse::<usize>().unwrap();
        let b =  inputiter.next().unwrap().parse::<usize>().unwrap();
        let c =  inputiter.next().unwrap().parse::<usize>().unwrap();
        (a,b,c)
    };
    let ans = {
        if let Some(x) = c.checked_sub(a-b){
            x
        }else{
            0
        }
    };
    println!("{}",ans);
}