#include <iostream>
#include <string>
using namespace std;
int main() {
string s1, s2;
cin >> s1 >> s2;
if(s2.find(s1) != stringnpos) {
cout << s1 << " is substring of " << s2 << endl;
}
else if(s1.find(s2) != stringnpos) {
cout << s2 << " is substring of " << s1 << endl;
}
else {
cout << "No substring" << endl;
}
}
