#include <iostream>
using namespace std;
long long int p, w;
int ww, ile;
int main()
{
cin>>ile;
if ((ile<=1)||(ile>=10))return 0;
for (int i=1; i<=ile; i++)
{
cin>>w>>p;
if (p!=0){ // to chyba zbędne
while (p>4)
{
p-=4;
}
if (p==1) ww=w;
if (p==2) ww=w*w;
if (p==3) ww=w*w*w;
if (p==4) ww=w*w*w*w;
cout << ww%10 << endl;
}
else cout << 0 << endl;
}
return 0;
}
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