#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
// --------------------------------------------------------
template<class T> bool chmax(T& a, const T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> bool chmin(T& a, const T b) { if (b < a) { a = b; return 1; } return 0; }
#define FOR(i,l,r) for (ll i = (l); i < (r); ++i)
#define RFOR(i,l,r) for (ll i = (r)-1; (l) <= i; --i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define SORT(c) sort(ALL(c))
#define RSORT(c) sort(RALL(c))
#define MIN(c) *min_element(ALL(c))
#define MAX(c) *max_element(ALL(c))
#define SUMLL(c) accumulate(ALL(c), 0LL)
#define COUNT(c,v) count(ALL(c),(v))
#define SZ(c) ((ll)(c).size())
#define BIT(b,i) (((b)>>(i)) & 1)
#define PCNT(b) __builtin_popcountll(b)
#define CIN(c) cin >> (c)
#define COUT(c) cout << (c) << '\n'
#define debug(x) cerr << "l." << __LINE__ << " : " << #x << " = " << (x) << '\n'
ll llceil(ll a, ll b) { return (a + b - 1) / b; }
ll bitlen(ll b) { if (b <= 0) { return 0; } return (64LL - __builtin_clzll(b)); }
string toupper(const string& S) { string T(S); REP(i,SZ(T)) T[i] = toupper(T[i]); return T; }
string tolower(const string& S) { string T(S); REP(i,SZ(T)) T[i] = tolower(T[i]); return T; }
using P = pair<ll,ll>;
using VP = vector<P>;
using VVP = vector<VP>;
using VS = vector<string>;
using VVS = vector<VS>;
using VLL = vector<ll>;
using VVLL = vector<VLL>;
using VVVLL = vector<VVLL>;
using VB = vector<bool>;
using VVB = vector<VB>;
using VVVB = vector<VVB>;
using VD = vector<double>;
using VVD = vector<VD>;
using VVVD = vector<VVD>;
using VLD = vector<ld>;
using VVLD = vector<VLD>;
using VVVLD = vector<VVLD>;
static const double EPS = 1e-10;
static const double PI  = acos(-1.0);
static const ll MOD = 1000000007;
// static const ll MOD = 998244353;
static const ll INF = (1LL << 62) - 1;  // 4611686018427387904 - 1
// --------------------------------------------------------
// #include <atcoder/all>
// using namespace atcoder;

// Editorial AC

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(15);

    ll N; cin >> N;
    VLL V(2*N); REP(i,2*N) cin >> V[i];

    priority_queue<ll,VLL,greater<ll>> pq;
    ll ans = SUMLL(V);
    REP(i,N) {
        pq.push(V[N-1-i]);
        pq.push(V[N+i]);
        ans -= pq.top(); pq.pop();
    }
    COUT(ans);

    return 0;
}

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int n,m;
int main(){
	cin>>n>>m;
	if(m==0){
		for(int i=1;i<=n;i++)printf("%d %d\n",i*2-1,i*2);
		return 0;
	}
	if(abs(m)>n-2||m<0)return puts("-1"),0;
	if(m>0){
		int now=2*m+4;
		printf("%d %d\n",1,2*m+3);
		printf("%d %d\n",2*m+2,2*m+4);
		for(int i=1;i<=m;i++)printf("%d %d\n",2*i,2*i+1);
		while(now<2*n)printf("%d %d\n",now+1,now+2),now+=2;
	}
	else {
		m=-m;
		int now=2*m+4;
		printf("%d %d\n",2,2*m+4);
		printf("%d %d\n",1,3);
		for(int i=1;i<=m;i++)printf("%d %d\n",2*i+2,2*i+3);
		while(now<2*n)printf("%d %d\n",now+1,now+2),now+=2;
	}
    return 0;
}