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

char duplisum(char cx) {
    int x,s=0;
    x = (cx - '0') * 2;
    while (x > 0) {
        s += x%10;
        x/=10;
    }
    return (s + '0');
}


char luhn(char *cn) {
     int p = 0;
     char d = '0';
     for (int i = 0; i < 15; i++) {
        d = cn[i];
        if (i%2==0) d = duplisum(d);
        p += (d - '0');
     }
     return (10 - (p % 10)) % 10 + '0';
}

int main() {
    char xx;    
    char cn[17] = {'0'};
    cin >> cn;
    
    xx = luhn(cn);
    
    if (cn[15] != xx) {
        cout << "Neispravan broj kartice! X = " << xx;     
    } else {
        cout << "Broj kartice je ispravan.";   
    }
    cout << endl;

    // system("pause");
    return 0;    
}