class Solution {
public:
    unordered_map<char,int> f;
    vector<pair<int,char>> need;

    bool check(int wind, string s){
        unordered_map<char,int> d;
        queue<char> q;
        for(char c : s){
            if(q.size()==wind){
                d[q.front()]--;
                q.pop();
            }
            d[c]++;
            q.push(c);

            //checar aqui
            int n = s.size();
            bool chec = true;
            for(auto p : need){
                chec &= d[p.second] >= p.first;
            }
            if(chec) return true;

        }

        return false;
    }

    int balancedString(string &s) {
        f['Q']=f['W']=f['E']=f['R'];

        for(char c : s)
            f[c]++;


        if(f['Q']==f['W'] and f['Q']==f['W'] and f['Q']==f['R']) return 0;

        int n = s.size();
        for(auto p : f)
            need.push_back({p.second-n/4,p.first});

        int l=0,r=s.size();
        for(auto p : need) if(p.first>0)l+=p.first;

        while(l<r){
            int mid = (l+r)/2;
            if(check(mid, s)) r=mid;
            else l = mid+1;
        }
        return l;
    }
};