Problem:
Score : 100 points

Problem Statement

You are given two integers A and B as the input. Output the value of A + B.

However, if A + B is 10 or greater, output error instead.

Constraints

A and B are integers.

1 ≤ A, B ≤ 9

Input

Input is given from Standard Input in the following format:

A B

Output

If A + B is 10 or greater, print the string error (case-sensitive); otherwise, print the value of A + B.

Sample Input 1

6 3

Sample Output 1

9

Sample Input 2

6 4

Sample Output 2

error

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

use std::fmt::Debug;
use std::io::{self, Read};
use std::str;
use std::str::FromStr;

fn main() {
    let mut sc = StdinScanner::new();
    let (a, b) = (sc.next::<u32>(), sc.next::<u32>());
    if a + b >= 10 {
        println!("error");
    } else {
        println!("{}", a + b);
    }
}


struct StdinScanner {
    buf: Vec<u8>,
}

impl StdinScanner {
    fn new() -> Self {
        StdinScanner { buf: Vec::with_capacity(256) }
    }

    fn next<T: FromStr>(&mut self) -> T
        where <T as FromStr>::Err: Debug
    {
        self.buf.clear();
        let stdin = io::stdin();
        let mut stdin = stdin.lock().bytes();
        let mut c = stdin.next().unwrap().unwrap();
        while c == ' ' as u8 || c == '\n' as u8 {
            c = stdin.next().unwrap().unwrap();
        }
        while !(c == ' ' as u8 || c == '\n' as u8) {
            self.buf.push(c);
            c = stdin.next().unwrap().unwrap();
        }
        str::from_utf8(&self.buf).unwrap().parse().unwrap()
    }
}