#include<stdio.h>
int main(){
    int size,ind,cnt;
    scanf("%d",&size);
    int arr[size];
    for(ind=0;ind<size;scanf(%d",&arr[ind++]));
    for(ind=0;ind<size;ind++){
        if(arr[ind]=1){
            arr[ind]=1;
            cnt++;
        }
    }
    if(cnt==size){
        printf("Invalid input");
        return 0;
    }
    for(ind=0;ind<size;printf("%d",arr[ind+]))
}