const targetStr = process.argv[2].toString();
const targetLength = targetStr.length;
const t = targetLength /2 - 1;

for (let c = t ; c != 0; c = c -1){
    let ttest = targetStr.slice(0, c*2);
    if (ttest.slice(0, c) == ttest.slice(c, c*2)) {
        console.log(c * 2);
        return;
    }
}