#include <iostream>//hetao3097453
using namespace std;
int main()
{
    int a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,sum = 0;
    cin >> a >> b >> c >> d >> e >> f >> g >> h >> i >> j >> k >> l >> m >> n >> o >> p >> q;
    a *= 7;
    b *= 9;
    c *= 10;
    d *= 5;
    e *= 8;
    f *= 4;
    g *= 2;
    h *= 1;
    i *= 6;
    j *= 3;
    k *= 7;
    l *= 9;
    m *= 10;
    n *= 5;
    o *= 8;
    p *= 4;
    q *= 2;
    sum += a + b + c + d + e + f + g + h + i + j + k + l + m + n + o + p + q;
    sum %= 11;
    if(sum == 0)
    {
        cout << 1 << endl;
    }
    else if(sum == 1)
    {
        cout << 0 << endl;
    }
    else if(sum == 2)
    {
        cout << "X" << endl;
    }
    else if(sum == 3)
    {
        cout << 9 << endl;
    }
    else if(sum == 4)
    {
        cout << 8 << endl;
    }
    else if(sum == 5)
    {
        cout << 7 << endl;
    }
    else if(sum == 6)
    {
        cout << 6 << endl;
    }
    else if(sum == 7)
    {
        cout << 5 << endl;
    }
    else if(sum == 8)
    {
        cout << 4 << endl;
    }
    else if(sum == 9)
    {
        cout << 3 << endl;
    }
    else if(sum == 10)
    {
        cout << 2 << endl;
    }
    return 0;
}