解

#include<iostream>
#include<string>
using namespace std;
int main(){
    string a,b;
    cin >>a>>b;
    if(a.find(b)!=-1)
        cout << b << " is substring of " << a;
    else if(b.find(a)!=-1)
        cout << a << " is substring of " << b;
    else
        cout << "No substring";
}