#include<bits/stdc++.h>
using namespace std;
int main()
{
	string a,b;
	cin>>a>>b;
	int c=a.size(),d=b.size();
	for(int i=1;i<=max(c,d);i++)
	{
		int e=0;
		for(int j=i;j<=min(c,d)+i;j++)
		{
			if(a[j]==b[j])
			{
				e++;
			}
		 } 
		 if(e==min(c,d))
		 {
		 	if(c>d)
		 	{
		 		cout<<b<<" is substring of "<<a<<endl;
			 }
			 else
			 {
			 	cout<<a<<" is substring of "<<b<<endl;
			 }
			 return 0;
		 }
	}
	cout<<"No substring";
	return 0;
}