Code:
#include <iostream>
using namespace std;
int main()
{
char c;
int n, br = 0, f = 1;
cin >> n;
for (int i=0; i<n; i++) {
cin >> c;
if (c=='(' || c=='[' || c=='{') ++br; else
if (c==')' || c==']' || c=='}') --br;
if (br < 0) {
cout << "greska";
f = 0;
break;
}
}
if (f && br==0) cout << "ok";
}