61. 石头剪刀布游戏

const readline = require('readline');
const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
});
let obj = {};
rl.on('line', function(line) {
    const [id, shape] = line.split(' ');
    obj[shape] = obj[shape] || [];
    obj[shape].push(id);
});
rl.on('close', () => {
    const shapes = Object.keys(obj);
    if (shapes.length !==2) {
        console.log('NULL');
        return;
    }
    let winids = [];
    if (obj['A'] && obj['B']) {
        winids = obj["A"];
    } else if (obj['B'] && obj['C']) {
        winids = obj['B'];
    } else if (obj['A'] && obj['C']) {
        winids = obj['C'];
    } else {
        console.log('NULL');
    }
    winids.sort();
    winids.forEach(id => console.log(id));
})