#include <stdio.h>
#include <string.h>
#include <stdlib.h>

typedef struct spolocne{
	char retazec[200];
	struct spolocne *dalsi; 
	}SPOLOCNE;

typedef struct prvky{
	SPOLOCNE *prvy,*akt;
	}PRVKY;

char *vyber(char s[],int o,int po){
	strncpy(s,(s+o),po);
	/*s=strcat(s,"\0");*/
	s[po]='\0';
	
	return(s);
}

void pridaj(PRVKY *p, char s[]){
	SPOLOCNE *pom;
	if (p->prvy==NULL){
		p->prvy=(SPOLOCNE *)malloc(sizeof(SPOLOCNE));
		strcpy(p->prvy->retazec,s);
		p->prvy->dalsi=NULL;
		p->akt=p->prvy;
		}
	else {
		pom=(SPOLOCNE *)malloc(sizeof(SPOLOCNE));
		strcpy(pom->retazec,s);
         	pom->dalsi=NULL;
		p->akt->dalsi=pom;
		p->akt=pom;
		}


}

void porovnaj(PRVKY *p, char s1[], char s2[]){
	int i,j;
	char spom2[200];
	char spom[200]; 
	for (i=0;i<strlen(s1);i++){
		for (j=1;j<(strlen(s1)-i+1);j++){
			strcpy(spom2,s1);
   		        strcpy(spom,vyber(spom2,i,j));
			printf("%s\n",spom);
			if (strstr(s2,spom)!=NULL) {
  				pridaj(p,spom);
				
				}	
			
			}
			
	}


}		

void kontrola(PRVKY *p,char s1[]){
	SPOLOCNE *pom;
	pom=p->prvy;
	while (pom!=NULL){
		if (strstr(s1,pom->retazec)==NULL){
			if (pom==p->prvy){
				pom=p->prvy->dalsi;
				free(p->prvy);
				p->prvy=pom;
				}
			else {
				p->akt=pom;
				pom=p->akt->dalsi;
				free(p->akt);
				}
			}
		
		else {
			pom=pom->dalsi;
			}	
		}
	free(pom);
}

char *najdinajm(PRVKY *p){
	SPOLOCNE *pom;
	pom=p->prvy;
	p->akt = p->prvy;
	while (pom!=NULL){
	
		if (strcmp(p->akt->retazec,pom->retazec)<0)p->akt=pom;
	}
	return(p->akt->retazec);
} 




int main(){
	int N;
	int i;
	char s1[200];
	char s2[200];
	PRVKY *p;
	p=(PRVKY*)malloc(sizeof(PRVKY));
	scanf("%d",&N);
	scanf("%s",s1);
	scanf("%s",s2);
	porovnaj(p,s1,s2);
	for (i=2;i<N;i++){
	scanf("%s",s1);
	/*kontrola(p,s1);*/	
	}
	if (p->prvy!=NULL)printf("%s\n",najdinajm(p));
	else printf("IDENTITY LOST\n");
	return 0;
}