#include<bits/stdc++.h>
using namespace std;
struct hui{
	string ci16;
	int ci,a;
}dt[300];
bool cmp(hui a,hui b){
	if(a.ci>b.ci)return 0;
	else return 1;
}
int main(void){
	int n,s=0;
	cin>>n;
	for(int xxxxx=0;xxxxx<n;xxxxx++){
		char a[25];
		cin>>a;
		char k[20];
		for(int i=0;i<sizeof(a);i++){
			if(a[i]==0)break;
            char ssss;
            ssss=a[i];
            //cout<<"aodjgaialgieu"<<endl; 
			if(i%2==0)k[0]=ssss;
            else k[1]=ssss;
			if(i%2==1){
				bool zhao=1;
				//cout<<"aodjgaialgieu"<<endl;
				for(int j=0;j<s;j++){
					if(dt[j].ci16==k){
						dt[j].ci++;
						zhao=0;
					} 
				}if(zhao){
					//cout<<"aodjgaialgieu"<<endl;
					int shu=0;
					if(k[0]>='A'&&k[0]<='F')shu+=int(k[0]-'A'+10)*16;
					else shu+=int(k[0]-'0')*16; 
					if(k[1]>='A'&&k[1]<='F')shu+=int(k[1]-'A'+10);
					else shu+=int(k[1]-'0');
					dt[s].a=shu;
					dt[s].ci=0;
					dt[s].ci16=k;
					//k[0]=k[1]=0;
					s++;
				}
			}
		}
	}
	//cout<<"aodjgaialgieu"<<endl;
	sort(dt,dt+s,cmp);
	for(int i=0;i<16;i++){
		if(s==16)break;
		cout<<dt[i].ci16;
		
	}
    return 0;
} 

RE在"ssss=a[i];"这一行