// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(S) {
    // write your code in JavaScript (Node.js 4.0.0)
    if (S.length==0) return 1;

    var stek= [];
    if(S[0]=="{" || S[0]=="[" || S[0]=="(") stek.push(S[0]);
    else return 0;

    for (var i=1; i<S.length; i++){
        switch (S[i]){
            case "{":  stek.push(S[i]); break;
            case "[":  stek.push(S[i]); break;
            case "(":  stek.push(S[i]); break;
            case "}":  if (stek[stek.length-1]=="{") stek.pop(); break;
            case "]":  if (stek[stek.length-1]=="[") stek.pop(); break;
            case ")":  if (stek[stek.length-1]=="(") stek.pop(); break;
        }
    }
    if (stek.length == 0) return 1;
    else return 0;
}

100%, 80%