import java.io.IOException; 
import java.io.InputStream; 
import java.io.PrintWriter; 
import java.util.*; 
 

class Main{
	static class Node{
		int v;
		long d;
		Node(int v, long d){this.v=v;this.d=d;}
	}

	static long dfs(int v, long dep){
		long res = dep;
		for(int u: edges[v])res += dfs(u, dep+1);
		return res;
	}
	static List<Integer> edges[];

	static void solve(){
		int n = ni();
		List<Node> nodes = new ArrayList<>();
		Map<Long, Integer> dtoi = new HashMap<>();
		for(int i=0;i<n;++i){
			long d=nl();
			nodes.add(new Node(i, d));
			dtoi.put(d, i);
		}
		Collections.sort(nodes, (a,b)->b.d-a.d<0 ? -1:1);
		long[] s = new long[n];
		int[] pare = new int[n];
		edges = new List[n];
		for(int i=0;i<n;++i)edges[i] = new ArrayList<>();
		Arrays.fill(pare, -1);
		Arrays.fill(s, 1);
		for(int i=0;i<n-1;++i){
			Node node = nodes.get(i);
			if(!dtoi.containsKey(node.d+2*s[node.v]-n) || node.v == dtoi.get(node.d+2*s[node.v]-n)){
				out.println(-1);return;
			}
			int p = dtoi.get(node.d+2*s[node.v]-n);
			pare[node.v] = p;
			edges[p].add(node.v);
			s[p] += s[node.v];
		}
		if(dfs(nodes.get(n-1).v, 0) != nodes.get(n-1).d){
			out.println(-1);return;
		}

		for(int i=0;i<n;++i){
			if(pare[i]<0)continue;
			out.println((i+1)+" "+(pare[i]+1));
		}

	}
 
 
 
 
	 public static void main(String[] args){ 
		 solve(); 
		 out.flush(); 
	 } 
	 private static InputStream in = System.in; 
	 private static PrintWriter out = new PrintWriter(System.out); 
 
	 static boolean inrange(int y, int x, int h, int w){ 
		 return y>=0 && y<h && x>=0 && x<w; 
	 } 
	 @SuppressWarnings("unchecked") 
	 static<T extends Comparable> int lower_bound(List<T> list, T key){ 
		 int lower=-1;int upper=list.size(); 
		 while(upper - lower>1){ 
		 int center =(upper+lower)/2; 
		 if(list.get(center).compareTo(key)>=0)upper=center; 
		 else lower=center; 
		 } 
		 return upper; 
	 } 
	 @SuppressWarnings("unchecked") 
	 static <T extends Comparable> int upper_bound(List<T> list, T key){ 
		 int lower=-1;int upper=list.size(); 
		 while(upper-lower >1){ 
		 int center=(upper+lower)/2; 
		 if(list.get(center).compareTo(key)>0)upper=center; 
		 else lower=center; 
		 } 
		 return upper; 
	 } 
	 @SuppressWarnings("unchecked") 
	 static <T extends Comparable> boolean next_permutation(List<T> list){ 
		 int lastIndex = list.size()-2; 
		 while(lastIndex>=0 && list.get(lastIndex).compareTo(list.get(lastIndex+1))>=0)--lastIndex; 
		 if(lastIndex<0)return false; 
		 int swapIndex = list.size()-1; 
		 while(list.get(lastIndex).compareTo(list.get(swapIndex))>=0)swapIndex--; 
		 T tmp = list.get(lastIndex); 
		 list.set(lastIndex++, list.get(swapIndex)); 
		 list.set(swapIndex, tmp); 
		 swapIndex = list.size()-1; 
		 while(lastIndex<swapIndex){ 
		 tmp = list.get(lastIndex); 
		 list.set(lastIndex, list.get(swapIndex)); 
		 list.set(swapIndex, tmp); 
		 ++lastIndex;--swapIndex; 
		 } 
		 return true; 
	 } 
	 private static final byte[] buffer = new byte[1<<15]; 
	 private static int ptr = 0; 
	 private static int buflen = 0; 
	 private static boolean hasNextByte(){ 
		 if(ptr<buflen)return true; 
		 ptr = 0; 
		 try{ 
			 buflen = in.read(buffer); 
		 } catch (IOException e){ 
			 e.printStackTrace(); 
		 } 
		 return buflen>0; 
	 } 
	 private static int readByte(){ if(hasNextByte()) return buffer[ptr++]; else return -1;} 
	 private static boolean isSpaceChar(int c){ return !(33<=c && c<=126);} 
	 private static int skip(){int res; while((res=readByte())!=-1 && isSpaceChar(res)); return res;} 
 
	 private static double nd(){ return Double.parseDouble(ns()); } 
	 private static char nc(){ return (char)skip(); } 
	 private static String ns(){ 
		 StringBuilder sb = new StringBuilder(); 
		 for(int b=skip();!isSpaceChar(b);b=readByte())sb.append((char)b); 
		 return sb.toString(); 
	 } 
	 private static int[] nia(int n){ 
		 int[] res = new int[n]; 
		 for(int i=0;i<n;++i)res[i]=ni(); 
		 return res; 
	 } 
	 private static long[] nla(int n){ 
		 long[] res = new long[n]; 
		 for(int i=0;i<n;++i)res[i]=nl(); 
		 return res; 
	 } 
	 private static int ni(){ 
		 int res=0,b; 
		 boolean minus=false; 
		 while((b=readByte())!=-1 && !((b>='0'&&b<='9') || b=='-')); 
		 if(b=='-'){ 
			 minus=true; 
			 b=readByte(); 
		 } 
		 for(;'0'<=b&&b<='9';b=readByte())res=res*10+(b-'0'); 
		 return minus ? -res:res; 
	 } 
	 private static long nl(){ 
		 long res=0,b; 
		 boolean minus=false; 
		 while((b=readByte())!=-1 && !((b>='0'&&b<='9') || b=='-')); 
		 if(b=='-'){ 
			 minus=true; 
			 b=readByte(); 
		 } 
		 for(;'0'<=b&&b<='9';b=readByte())res=res*10+(b-'0'); 
		 return minus ? -res:res; 
	} 
} 



Measured memory_bytes: 77364