#include<iostream>
#include<string.h>
using namespace std;
string s1,s2;
int main() {
	getline(cin,s1);
	getline(cin,s2);
	if(s2.find(s1)!=string::npos) {
		cout<<s1<<" is substring of "<<s2<<endl;
		return 0;
	} else {
		if(s1.find(s2)!=string::npos) {
			cout<<s2<<" is substring of "<<s1<<endl;
			return 0;
		} else {
			cout<<"No substring"<<endl;
			return 0;
		}
	}
	return 0;
}