#include <bits/stdc++.h>
using namespace std;
int main()
{
	int a,b[20],c[20]={7,9,10,5,8,4,2,1,6,3,7,9,10,5,8,4,2},i,s=0;
	//c数组存放各个数的系数，
	char d[20]={'1','0','X','9','8','7','6','5','4','3','2'};
	//余数对应的字符
	for(i=0;i<17;i++)
	{
		cin>>a;
		s+=a*c[i];//数字*系数
	}
	s%=11;//和%11的余数
	cout<<d[s]<<endl;//余数对应的字符
	return 0;
}