helpmefff

#include <iostream>
#include <string>
#include <stack>

using namespace std;

int main() {
    string st;
    cin >> st;
    stack <int> pool;
    int g = (int) st.size();
    for (int i=0 ; i<g ; i=i+1) {
        if (st[i]='(') {
            pool.push(1);
        }
        else if (st[i]='[') {
            pool.push(2);
        }
        else if (st[i]='{') {
            pool.push(3);
        }
        else if ((st[i]==')')&&(pool.top()=='1')) {
            pool.pop();
        }
        else if ((st[i]==']')&&(pool.top()=='2')) {
            pool.pop();
        }
        else if ((st[i]=='}')&&(pool.top()=='3')) {
            pool.pop();
        }
        else {
            printf("NOo");
            break;
        }
         printf("%d", pool.top());
         printf("%d", pool.size());
    }
    if (pool.size()!=0) {
        printf("NO");
    }
    else{
        printf("YES");
    }
}