#include<bits/stdc++.h>
using namespace std;
const int N = 1e6+10;
string a,b;

bool bj(string a,string b,int i){
    int flag =0;
    for(int j=0;j<a.size();j++){
        if(a[j]!=b[i]){
            flag = 1;
            return false;
        }
        i++;
    }
    if(flag==0){
        return true;
    }
    
}

int main(){
    cin>>a>>b;
    if(a.size()<=b.size())
    {
        int flag = 0;
        int n = b.size()-a.size()+1;
        for(int i=0;i<=n-1;i++){
            if(bj(a,b,i)){
                flag = 1;
                cout<<a<<" is substring of "<<b;
            }
        }
        if(flag == 0){
            cout<<"No substring";
        }
    }else{
        int flag = 0;
        int n = a.size()-b.size()+1;
        for(int i=0;i<=n-1;i++){
            if(bj(b,a,i)){
                flag = 1;
                cout<<b<<" is substring of "<<a;
            }
        }
        if(flag == 0){
            cout<<"No substring";
        }
    }
    return 0;
}