#include <bits/stdc++.h>
using namespace std;
int main() {
    string a,b;
    getline(cin,a);
    getline(cin,b);
    if(a.find(b)!=a.npos){
    	cout<<b<<" is substring of "<<a<<endl;
	}
	else if(b.find(a)!=b.npos){
		cout<<a<<" is substring of "<<b<<endl;
	}
    else cout<<"No substring"<<endl; 
}