#include <bits/stdc++.h>
using namespace std;

int main(){
    string a;string s;
    cin >> a >> s;
    bool flag = 0;
    for (int i = 0;i < s.size()-1;i++){
        for (int r = i;r < s.size();r++){
            if(s.substr(i,r-i) == a){
                cout << a <<" is substring of " <<s;
                flag = 1;
            }
        }
    }
    
    if(!flag){
        for (int i = 0;i < a.size()-1;i++){
            for (int r = i;r < a.size();r++){
                if(a.substr(i,r-i) == s){
                    cout << s <<" is substring of " << a;
                    flag = 1;
                }
            }
        }
    }
    if (!flag)  cout << "No substring";
    return 0;
}