Gemstones.txt

'use strict';

const fs = require('fs');

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', inputStdin => {
    inputString += inputStdin;
});

process.stdin.on('end', _ => {
    inputString = inputString.replace(/\s*$/, '')
        .split('\n')
        .map(str => str.replace(/\s*$/, ''));

    main();
});

function readLine() {
    return inputString[currentLine++];
}

function gemstones(arr) {
    let combined = arr.join('');
    let unique = [...new Set(combined)];
    let result = unique.filter(ch =>
        arr.every(str => str.includes(ch)));
    return result.length;

}

function main() {
    const ws = fs.createWriteStream(process.env.OUTPUT_PATH);

    const n = parseInt(readLine(), 10);

    let arr = [];

    for (let i = 0; i < n; i++) {
        const arrItem = readLine();
        arr.push(arrItem);
    }

    let result = gemstones(arr);

    ws.write(result + "\n");

    ws.end();
}