#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define db double
#define in inline
namespace fast_io
{
	char buf[1<<12],*p1=buf,*p2=buf,sr[1<<23],z[23],nc;int C=-1,Z=0;
	in char gc() {return p1==p2&&(p2=(p1=buf)+fread(buf,1,1<<12,stdin),p1==p2)?EOF:*p1++;}
	in ll read()
	{
		ll x=0,y=1;while(nc=gc(),(nc<48||nc>57)&&nc!=-1) if(nc==45) y=-1;
		x=nc-48;while(nc=gc(),47<nc&&nc<58) x=(x<<3)+(x<<1)+(nc^48);return x*y;
	}
	in db gf() {int a=read(),b=(nc!='.')?0:read(),c=ceil(log10(b));return (b?a+(db)b/pow(10,c):a);}
	in int gs(char *s) {char c,*t=s;while(c=gc(),c<32);*s++=c;while(c=gc(),c>32)*s++=c;return s-t;}
	template <typename T>
	in void write(T x,char t)
	{
		int y=0;if(x<0) y=1,x=-x;while(z[++Z]=x%10+48,x/=10);
		if(y) z[++Z]='-';while(sr[++C]=z[Z],--Z);sr[++C]=t;
	}
	in void write(char *s) {int l=strlen(s);for(int i=0;i<l;i++,*s++)sr[++C]=*s;sr[++C]='\n';}
	in void ot() {fwrite(sr,1,C+1,stdout);C=-1;}
};
using namespace fast_io;
#define fi first
#define se second
const int N=2e5+5;
int n,rt,k,a[N],c[N];
pair<int,int>p[N],ans[N];
set<pair<int,int> >s,t;
int main()
{
	n=read();int res=0;
	for(int i=1;i<=n;i++) a[i]=a[n+i]=read(),c[a[i]]++,!a[i]?rt=i:0;
	if(c[0]^1) return write("-1"),ot(),0;
	for(int i=rt;i<rt+n;i++) p[i-rt+1]={a[i],i};
	sort(p+1,p+n+1);s.insert({p[1].se,p[1].fi});
	for(int i=2;i<=n;i++)
	{
		if(p[i].fi^p[i-1].fi) {for(auto x:t) s.insert(x);t.clear();}
		if(p[i].fi==1) ans[++k]={rt,p[i].se};
		else
		{
			auto it=s.upper_bound({p[i].se,p[i].fi});
			if(it!=s.end()&&(*it).se==p[i].fi-1) ans[++k]={(*it).fi,p[i].se};
			else if((*--it).se==p[i].fi-1) ans[++k]={(*it).fi,p[i].se};
			else return write("-1"),ot(),0;
		}t.insert({p[i].se,p[i].fi});
	}
	for(int i=1;i<n;i++) write((ans[i].fi-1)%n+1,' '),write((ans[i].se-1)%n+1,'\n');
	return ot(),0;
}