#include <iostream>
#include <string>
using namespace std;
int main() {
	string a, b;
	int sum = 0;
	getline(cin, a);
	getline(cin, b);
	if (b.find(a) != string::npos) {
		cout << a << " is substring of " << b << endl;
		return 0;
	}
	else if (a.find(b) != string::npos) {

		cout << b << " is substring of " << a << endl;
	}
	else
		cout << "No substring";
	return 0;
}

#include<stdio.h>
#include<string.h>
int judge(char a[],char b[],int l1,int l2);
int main()
{
    char a[201],b[201];
    gets(a);
    gets(b);
    int rec;
    int l1=strlen(a);
    int l2=strlen(b);
    if(l1>=l2)
    rec=judge(a,b,l1,l2);
    else if(l1<l2)
    rec=judge(b,a,l2,l1);
    if(rec)
    {
        if(l1>=l2)
        printf("%s is substring of %s",b,a);
        else if(l1<l2)
        printf("%s is substring of %s",a,b);
    }
    else
    printf("No substring");
    return 0;
}
int judge(char a[],char b[],int l1,int l2)
{
    int i,j;
    int count=0;
    int flag=0;
	int n=0;
    for(i=0;i<l1;i++)
    {
        if(a[i]==b[n])
        {
        n++;
        count++;
        if(count==l2)
        {
        flag=1;
        break;
        }
        }
        else
        { 
        count=0;
        n=0;
        }
    }
    return flag;
}