"use strict";

process.stdin.resume();
process.stdin.setEncoding('utf8');

var g_input = '';
process.stdin.on('data', function(chunk) {
    g_input += chunk;
});

process.stdin.on('end', function() {
    Main(g_input.split(/\r?\n/));
});

function Main(input) {

    const n = parseInt(input[0], 10);

    let ans = 0;
    if (n % 2 === 0) {
        ans = n;
    }
    else {
        ans = n * 2;
    }

    console.log(ans);

    return 0;
}
