70

//[1]1 [2]1 [3]0 [4]0 [5]1 [6]1 [7]1 [8]0 [9]1 [10]1 [11]0 [12]0
#include <bits/stdc++.h>
using namespace std;
bool s[98965487];
bool si[98965487];
int main(){
	int t,sh=0;
	cin>>t;
	sh=t;
	for(int i=1;i<=t;i++){
		cin>>s[i];		
	}
	for(int j=1;sh!=0;j++){
		int ii=-1;
		for(int i=1;i<=t;i++){
			if(si[i]!=1 and s[i]!=ii){
				cout<<i<<" ";
				ii=s[i];
				si[i]=1;
				sh--;
			}		
		}
		//for(int i=1;i<=t;i++){
		//	cout<<" 6 6 6 "<<si[i]<<" ";		
		//}
		cout<<endl;	
	}		
	//for(int i=1;i<=t;i++){
	//	cout<<s[i]<<" ";		
	//}
	return 0;
}