if __name__ == '__main__':
    t = int(input())
    for i in range(t):
        n = int(input())
        flag = True
        aIN = 0
        bIN = 0
        tab=[None]*n
        for z in range(n):
            tab[z]=input()
        for j in range(n):
            # napis = input()
            if tab[j] == "AI":
                aIN += 1
            elif tab[j] == "AO":
                bIN -= 1
            elif tab[j] == "BI":
                bIN += 1
            elif tab[j] == "BO":
                aIN -= 1
            if aIN < 0 or bIN < 0:
                flag = False
                break
        if flag:
            print(aIN + bIN)
        else:
            print("ERROR")
 

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Mgo3CkFJCkJPCkJJCkJJCkFPCkFJCkFPCjQKQU8KQUkKQUkKQkk=

2
7
AI
BO
BI
BI
AO
AI
AO
4
AO
AI
AI
BI