#include<fstream.h>
#define input "cifra.in"
#define output "cifra.out"

int main()
	{
	char a[110];
	int t,ans[10][10],i,j,s,k,div,mod;
	ifstream fin(input);
	ofstream fout(output);
	fin>>a;
	ans[0][0]=0;
	for(i=1;i<=99;i++)
		{
		ans[i/10][i%10]=0;
		for(j=1;j<=i;j++)
			{
			s=j;
			for(k=2;k<=j;k++)
				{
				s=s%10;
				s=s*j;
				}
			ans[i/10][i%10]+=s;
			}
		ans[i/10][i%10]%=10;
		}
	fin>>t;
	while(t)
		{
		fout<<ans[(t/10)%10][t%10]<<"\n";
		t=0;
		fin>>t;
		}
	return 0;
	}