t=int(input())
for i in range(t):
    n=int(input())
    s=input()
    count=0
    odd=0
    S=list(s)
    for j in range(n):
        if S[j]=='0':
            for c in range(j+1,n):
                if S[c]=='1':
                    S[j],S[c]=S[c],S[j]
                    count+=1


    for k in range(n):
        if S[k]=='1':
            for b in range(k+1,n):
                if S[b]=='0':
                    S[k],S[b] = S[b],S[k]
                    odd += 1



    if count<odd:
        print(count)
    elif odd<count:
        print(odd)
    elif odd==count:
        print(odd)