#include <cstdio>
#include <algorithm>
using namespace std;
int main(){
int n;
while(scanf("%d\n",&n) != EOF){
int arr[n];
for (int i=0;i<n;i++){
scanf("%d",&arr[i]);
}
sort(arr,arr+n);
printf("%d\n",arr[n-1]);
arr[n-1]=0;
if (arr[0]==0){
printf("%d",-1);
}
if(arr[0] != 0){
for (int i=0;i<n;i++){
if(arr[i] != 0){
printf("%d ",arr[i]);
}
}
}
}
return 0;
}



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