#include <stdio.h>
#include <stdlib.h>
#include <string.h>
// Yukicoder №164 ちっちゃくないよ！！ ★★
// https://yukicoder.me/problems/no/164
// ***********************
#define PRINCR do{printf("\n");fflush(stdout);}while(0)
#define GETLINE(str) do{char *p;fgets(str,sizeof(str),stdin);p=strchr(str,'\n');if(p)*p='\0';}while(0)
#define REP(a,b) for(int a=0;a<(int)(b);++a)
static char *GETWORD(char* str) {char c;char *cp;cp=&str[0];c=fgetc(stdin);while( c != EOF ){if((c==' ')||( c=='\n')) break;*cp++=c;c=fgetc(stdin);}*cp='\0';return &str[0];}
#define	GETINTS(a,b) {char s[34];int *ap=a;REP(i,b){GETWORD(s);sscanf(s,"%d", ap);ap++;}}
static int GETLINEINT(void) {char s[34];GETLINE(s);return atoi(s);}
static int GETWORDINT(void) {char s[34];GETWORD(s);return atoi(s);}
#define Yes(a)	  printf("%s",((a)?"Yes":"No"))
long long miniatoi( char *str ) {
	int	lank;
	int	start;
	long long val;
	char	*cp;
	char *endptr;
	int	col;
	long long	mini = 4738381338321616893;

	cp = str;
	start = 0;
	while( *cp != '\0' ) {
		if( start < *cp ) start = *cp;
		cp++;
	}
	endptr = cp;
	if( start <= '9' ) {
		start = start - '0';
	} else {
		start = start - 'A' +10;
	}
	start += 1;
	if( start < 2 ) start = 2;
	if( start > 36) start = 36;
	mini = strtol( str , &endptr , start );
	return mini;
}
int main() {
	char	st[24];
	int		query;
	long long val;
	long long minim = 4738381338321616893;

	query = GETLINEINT();
	REP(i,query) {
		GETLINE(st);
		val = miniatoi( st );
		if( val < minim ) minim = val;
	}
	printf("%lld\n",minim);
	return 0;
}