题解

#include <bits/stdc++.h>
using namespace std;
int main(){
string a,b,c;
cin>>a>>b>>c;
string s1=a+b;
if(s1.find(c)!=string::npos) cout<<c<<" is substring of "<<a<<" and "<<b<<endl;
else cout<<c<<" is not substring of "<<a<<" and "<<b<<endl;
return 0;
}