#include<bits/stdc++.h>
using namespace std;
char s1[30],s2[30];
int main(){
	gets(s1);
	gets(s2);
	if(strstr(s1,s2)){
		cout << s2 << " is substring of " << s1;
	} else if(strstr(s2,s1)){
		cout << s1 << " is substring of " << s2;
	} else{
		cout << "No substring";
	}
	return 0;
}