function sum(a,b){
    const add = a+b;
    if(add >= 10){
        return "error";
    }
    return add;
}

const readline = require("readline");
const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout
});

rl.question("Give me A=", function(x) {
    rl.question("Give me B=", function(y) {
        const value1 = parseInt(x);
        const value2 = parseInt(y);
        const result = sum(value1,value2);
        console.log(result);
        rl.close();
    });
});