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)

mod reader {
    use std::fmt::Debug;
    use std::str::FromStr;
    use std::collections::VecDeque;
    use std::io::{self, Read};

    fn _read_line() -> String {
        let mut buf = String::new();
        io::stdin().read_to_string(&mut buf);
        buf
    }

    fn _read_vec_deque_string() -> VecDeque<String> {
        _read_line().split_whitespace().map(|s| s.to_string()).collect()
    }

    pub struct Reader {
        buf: VecDeque<String>
    }

    impl Reader {
        pub fn new() -> Reader {
            Reader {buf: VecDeque::new()}
        }

        fn update_buf(&mut self) {
            if self.buf.is_empty() {
                self.buf = _read_vec_deque_string();
            }
        }

        pub fn next<T>(&mut self) -> T where T: FromStr, T::Err: Debug {
            self.update_buf();
            self.buf.pop_front().unwrap().parse::<T>().unwrap()
        }

        pub fn nextN<T>(&mut self, n: usize) -> Vec<T> where T: FromStr, T::Err: Debug {
            let mut vec: Vec<T> = Vec::with_capacity(n);
            for i in 0..n {
                vec.push(self.next());
            }
            vec
        }
    }
}

mod data {
    pub struct UnionFind {
        root : Vec<usize>
    }

    impl UnionFind {
        pub fn new(size : usize) -> UnionFind {
            UnionFind {root : (0..size).collect()}
        }

        pub fn find(&mut self, x : usize) -> usize {
            let xroot = self.root[x];
            if x != xroot {
                self.root[x] = self.find(xroot);
            }
            self.root[x]
        }

        pub fn unite(&mut self, x : usize, y : usize) {
            let xroot = self.find(x);
            self.root[xroot] = self.find(y);
        }

        pub fn same(&mut self, x : usize, y : usize) -> bool {
            self.find(x) == self.find(y)
        }
    }
}

fn with_large_stack(func : fn() -> ()) {
    use std::thread::Builder;
    let builder = Builder::new();
    let th = builder.stack_size(10000000);

    th.spawn(move || {
        func();
    }).unwrap().join();
}

fn main() {
    with_large_stack(_main);
}

fn _main() {
    let mut reader = reader::Reader::new();

    let a: i32 = reader.next();
    let b: i32 = reader.next();
    if a + b >= 10 {
        println!("error");
    } else {
        println!("{}", a + b);
    }
}