#include <iostream>
#include <vector>

using namespace std;

int findMissingISBN(string isbn){
    vector<int> digits;
    bool foundMissing = false;
    int sum = 0, missingPosition = -1, result, cntDashes = 0;

    for(int i = 0; i < isbn.length(); i++){
        if(isbn.at(i) == '-' && !foundMissing){
            cntDashes++;
        }
        if(isbn.at(i) == '?'){
            missingPosition = i;
            foundMissing = true;
            digits.push_back(0);
            continue;
        }
        if(isbn.at(i) != '-' && (isbn.at(i) != 'X' || isbn.at(i) != 'x')){
            digits.push_back((int)(isbn.at(i) - 48));
        }
        if(isbn.at(i) == 'X' || isbn.at(i) == 'x'){
            digits.push_back(10);
        }
    }

    for(int i = 0; i < digits.size(); i++){
        sum += ((digits.at(i) * (i + 1)) % 11);
    }

    missingPosition -= cntDashes - 1;

    if(missingPosition < 0){
        throw invalid_argument("The missing digit must be marked as \"?\"!");
    } else {
        for(int i = 1; i <= 11; i++){
            int curr = sum + (missingPosition * i);
            if(curr % 11 == 0){
                return i;
            }
        }
    }
}

int main() {
    // must put ? on the missing element
    // 0-19-85?803-0
    // and the element is 3
    string isbn;
    cin >> isbn;
    cout << findMissingISBN(isbn);

    return 0;
}