#include <iostream>
using namespace std;
int main(){
int t;
cin >> t;
while(t--){
int z, osoby = 0, osoby1 = 0, error = 0;
cin >> z;
while(z--){
string czujnik;
cin >> czujnik;
if(czujnik == "AI") {
osoby++;
}
else if(czujnik == "BI") {
osoby1++;
}
else if(czujnik == "AO") {
osoby1--;
}
else if(czujnik == "BO") {
osoby--;
}
if(osoby < 0 || osoby1 < 0) {
cout << "ERROR" << endl;
error++;
break;
}
}
if(error == 0)
cout << osoby + osoby1 << endl;
}
}
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