LASTDIG.cpp

#include <iostream>
using namespace std;

int power(int a, int b)
{
	if (b == 0) return 1;

	if(b % 2 == 0)
	{
		int t = power(a, b/2);
		return t*t;
	}
	else
	{
		int t = power(a, (b - 1) / 2);
		return t*t*a;
	}
}

int main()
{
	ios::sync_with_stdio(false);
	freopen("input.txt","r",stdin);
	
	int T;
	unsigned int a, b;
	int last_digit;

	cin >> T;
	for(int tc = 0; tc < T; tc++)
	{
		cin >> a >> b;
		if(b == 0) last_digit = 1;
		else 
		{
			int x = a % 10;
			int y = b % 4;
			if (y == 0) y = 4;

			last_digit = power(x, y) % 10;
		}
		cout << last_digit << endl;
	}
	return 0;
}