#include <iostream>
using namespace std;
int main()
{
int T;
cin>>T;
long N;
long C=0;
while (T!=0)
{
cin>>N;
char A[100000];
C=N-1;
for (int i=0;i<2*(N-1);i++)
cin>>A[i];
for (int i=0;i<2*N-3;i=i+2)
{
if (A[i]==A[i+1]+32)
C--;
}
cout<<C<<'\n';
C=0;
T--;
}
return 0;
}
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