#include <iostream>
#include <vector>
#include <bitset>
#include <utility>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>
#include <cmath>
#include <map>
#include <set>
 
using namespace std;
typedef long long ll;
 
int main(){
  ll n,m;
  cin >> n >> m;
  if(n==1 && m==0){
    cout << 1 << " " << 2 << endl;
    return 0;
  }else if(m<0 || n-2<m){
    cout << -1 << endl;
    return 0;
  }
  for (ll i = 0; i < n-1; i++){
    cout << 3*i+3 << " " << 3*i+1+3 << endl;
  }
  cout << 3*(n-m-2)-1+3 << " " << 3*n << endl; 
  
  return 0;
}

// KNOW NOTHING!
#include <bits/stdc++.h>
#define ll long long int
#define F(i,j,k,in) for(int i=j;i<k;i+=in)
#define DF(i,j,k,in) for(int i=j;i>=k;i-=in)
#define feach(it,l) for (auto it = l.begin(); it != l.end(); ++it)
#define fall(a) a.begin(),a.end()
#define sz(x) (int)x.size()
#define szs(x) (int)x.length()
#define pb push_back
#define ub upper_bound
#define lb lower_bound
#define eq equal_range
#define fs first
#define ss second
#define ins insert
#define mkp make_pair
#define endl "\n"
using namespace std;
typedef vector<ll> vll;
typedef vector<int> vin;
typedef vector<char> vch;
typedef vector<string> vst;
typedef set<ll> sll;
typedef set<int> sint;
typedef set<char> sch;
typedef set<string> sst;
typedef queue<ll> qll;
typedef queue<int> qin;
typedef deque<ll> dqll;
typedef deque<int> dqint;
typedef priority_queue<ll> pqll;
typedef priority_queue<int> pqin;
typedef map<ll,ll> mpll;
typedef map<int,int> mpin;
typedef pair<ll,ll> pll;
typedef pair<int,int> pin;
const ll MOD=1000000007;
const long double PI=3.1415926535897932384626433832795;
ll pwr(ll b,ll p){ll res=1;while(p){if(p&1) {res*=b; p--;}else{b*=b; p>>=1;}}return res;}
ll mpwr(ll b,ll p){ll res=1;while(p){if(p&1) {res=(res*b)%MOD; p--;}else{b=(b*b)%MOD; p>>=1;}}return res;}
int msb (int n) {return 31-__builtin_clz(n);}
ll msbl (ll n) {return 63-__builtin_clzll(n);}
int lsb (int n) {return __builtin_ctz(n);}
ll  lsbl (ll n) {return __builtin_ctzll(n);}
int setbit (int n) {return __builtin_popcount(n);}
ll setbitl (ll n) {return __builtin_popcountll(n);}
int main()
{
/*
freopen ("input.txt","r","stdin");
freopen ("output.txt","w","stdout");
*/
ios_base::sync_with_stdio(false) , cin.tie(NULL) , cout.tie(NULL);
int n; cin>>n;
vector <pair<int,string>> v (n);
F (i,0,n,1) {
	cin>>v[i].ss>>v[i].fs;
}
sort (fall (v)); reverse (fall (v));
cout<<v[1].ss;
}
/* What we know is a drop , but what we don't know is an ocean !*/