#include<iostream>
#include<string>
using namespace std;
string a,b,c;
bool check(){
	int i=0,j=0,k=0;
	int alen=a.length(),blen=b.length(),clen=c.length();
	if(a.at(alen-1)!=c.at(clen-1)&&b.at(blen-1)!=c.at(clen-1))return false;
	while(k<clen){
		if(i<alen&&j<blen&&c.at(k)==a.at(i)&&c.at(k)==b.at(j)){
			int ti=i,tj=j,tk=k;
			while(i<alen&&j<blen&&c.at(k)==a.at(i)&&c.at(k)==b.at(j)){
				i++;j++;k++;
			}
			if(i<alen&&j<blen&&c.at(k)!=a.at(i)&&c.at(k)!=b.at(j)){
				if(c.at(k)!=a.at(ti)&&c.at(k)!=b.at(tj)){
					return false;
				}else{
					if(i<alen&&c.at(k)==a.at(i))i=ti;
					else j=tj;
				}
			}else{
				if(i<alen&&c.at(k)==a.at(i))j=tj;
				else i=ti;
			}
		}else if(i<alen&&c.at(k)==a.at(i)){
			i++;k++;
		}else if(j<blen&&c.at(k)==b.at(j)){
			j++;k++;
		}else{
			return false;
		}
	}
	return (i+j)==k;
}
int main()
{
	freopen("in.txt","r",stdin);
	int t;
	cin>>t;
	int test=1;
	while(t--){
		cin>>a>>b>>c;
		cout<<"Data set "<<test++<<": "<<(check()?"yes":"no")<<endl;
	}
	return 0;
}
这样写也不对~~不知道哪里错了