Sum of Nodes in Kth Level SRBD

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

int main(){
    int k;
    cin >> k;
    string s;
    cin >> s;
    int level=-1;
    int sum=0;

    for(int i=0; i<s.size(); i++){
        if(s[i]=='('){
            level++;
        }
        else if(s[i]==')'){
            level--;
        }
        else if(level==k){
            int value=0;
            while(s[i]!='(' and s[i]!=')'){
                value= value*10+s[i]-'0';
                i++;
            }
            i--;
            sum+=value;
        }
    }

    cout << sum << endl;
    return 0;


}