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)

fn main() {
    let (a, b) = {
        let v = mylib::get_ints();
        (v[0], v[1])
    };
    println!("{}", match a + b { v if v < 10 => (a + b).to_string(), v => "error".to_string() })
}

mod mylib {
    // IO
    pub fn get_str() -> String {
        use std::io;
        let mut input = String::new();
        io::stdin().read_line(&mut input);
        input.as_str().trim().to_string()
    }
    fn split_by_space(ss:&str) -> Vec<&str> {
        ss.split_whitespace().collect()
    }
    fn str_to_int(ss:&str) -> i64 {
        ss.parse().unwrap()
    }
    pub fn get_ints() -> Vec<i64> {
        split_by_space(&get_str()).iter().map(|s:&&str| str_to_int(s)).collect()
    }
}