#include "stdafx.h"
#include "stdio.h"
#include "stdlib.h"
#include"math.h"

int count (int a){
	int j=0;
	while (a>0){
		j++;
		a=a/10;}
	return j;
}
int conunct(int b,int c){
	int *f;
	int *f1;
	int *f2;
	int g=0, g1=0,l=0,k=0;;
	int d=count(b);
	if (count(b)>count(c))
     d=count(c)+(count(b)-count(c));
	if (count(c)>count(b))
	 d=count(b)+(count(c)-count(b));
    f=(int*)calloc(d,sizeof(int));
	f1=(int*)calloc(d,sizeof(int));
	f2=(int*)calloc(d,sizeof(int));
	while (b!=0){
		f[g]=b % 10;
		b=b/10;
		g++;}
	while(c!=0){
		f1[g1]=c % 10;
		c=c/10;
		g1++;}
	for(int i=0;i<d;i++)
    f2[i]=f[i]*f1[i];
for (int i=0;i<d;i++){
l=l+f2[i]*pow((double)10,k);
	k++;}
return l;}
int main()
{
	int n;
	scanf("%d", &n);
	int *a;
	a=(int*)malloc(n*sizeof(int));
	for (int i=0;i<n;i++){
		scanf("%d", &a[i]);
	}
	int c;
	c=conunct(a[0],a[1]);
	for (int i=2;i<n;i++)
		c=conunct(c,a[i]);
	printf("%d", c);
	scanf("%d", &n);
	return 0;
}