#include <stdio.h>
int main() {
int N;
scanf("%d",&N);
int arr[N];
int i, zeroFound=0;
for (i=0;i<N;i++){
scanf("%d",&arr[i]);
if(arr[i]==0)
zeroFound=1;
}
if(!zeroFound){
printf("Invalid input");
return 0;
int index=0;
for (i=0;i<N;i++){
if (arr[i]!=0){
arr[index++]=arr[i];
}
}
while(index<N){
arr[index++]=0;
}
for(i=0;i<N;i++){
printf("%d",arr[i]);
}
 return o;
}