Sum of Nodes in Kth Level

#include<bits/stdc++.h>
using namespace std;

int main(){
    int k;
    cin >> k;
    string s;
    cin >> s;
    int level = -1, sum = 0, n = s.size(), value = 0;
    for(int i = 0; i < n; i++){
        if(s[i] == '(') level++;
        else if(s[i] == ')') level--;
        else if(level == k){
            if(s[i] == '-'){
                i++;
                value = 0;
                while(s[i]!='(' and s[i]!= ')' and s[i]>='0' and s[i]<='9'){
                    value = value * 10 + s[i]-'0';
                    i++;
                }
                i--;
                value = - value;
                sum+=value;
            }
            else{
                value = 0;
                while(s[i]!='(' and s[i]!= ')' and s[i]>='0' and s[i]<='9'){
                    value = value * 10 + s[i]-'0';
                    i++;
                }
                i--;
                sum+=value;
            }
        }
    }
    cout << sum << endl;
}

/*
2
(0(5(16()())(4()(9()())))(7(1()())(3()())))

24
*/