Transfusion Chain

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

int main() {
    int t;
    cin>>t;

    while(t--)
    {
        int n;
        cin>>n;

        vector<string> v(n);
        for(auto &e: v)     cin>>e;

        map<string, int> mp;
        for(auto e: v)
            mp[e]++;

        int ans = max(mp["O"]+mp["A"]+mp["AB"],
                      mp["O"]+mp["B"]+mp["AB"]);

        cout<<ans<<"\n";
    }
}