isbn

#include <iostream>
#include <vector>
using namespace std;

int main () {
	vector<char> v(10);
	int incognita;
	bool condicio = true;
	for (int i = 0; i < 10; ++i) {
		condicio = condicio and (cin >> v[i]);
		if (condicio and v[i] == '?') incognita = i;
	}
	incognita = 10 - incognita;
	while (condicio) {
		int suma = 0;
		int j = 10;
		for (int i = 0; i < 10; ++i) {
			if (v[i] != '?') {
				if (v[i] == 'X') suma += 10 * j;
				else suma += (v[i] - '0') * j;
			}
			--j;
		}
		for (int i = 0; i <= 10 ; ++i) {
			if ((suma + i * incognita) % 11 == 0) {
				if (i == 10) cout << "X" << endl;
				else cout << i << endl;
			}
		}
		for (int i = 0; i < 10; ++i) {
			condicio = condicio and (cin >> v[i]);
			if (condicio and v[i] == '?') incognita = i;
		}
		incognita = 10 - incognita;
	}
}