WRONG ANS TO BE CHECKED

class Solution {
public:
    int findTheLongestBalancedSubstring(string s) {
        int n=s.length();
    vector<string> v;
    for (int len = 1; len <= n; len++) {
        for (int i = 0; i <= n - len; i++) {
            int j = i + len - 1;
            string st=s.substr(i, len);
            v.push_back(st);
        }
    }
        int ans=-1;
        for(int i=0;i<v.size();i++)
        {


            if(v[i].length()%2==0 && v[i][0]=='0')
            {
                unordered_map<char,int> m;
                for(int j=0;j<v[i].length();j++)
                {
                    m[v[i][j]]++;
                }
                for(int k=0;k<v[i].length();k++)
                {
                    if(v[i][k]=='1' && m[0]!=0)
                    {
                        break;
                    }
                    else
                    {
                           m[v[i][k]]--;
                    }
                }
                if(m[0]==0 && m[1]==0)
                {
                    ans=max(ans,v[i].length());
                }

            }

        }
        return ans;

    }
};