Submission #6063110

---

Source Code Expand

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define ft first
#define sd second
#define fr(i,n) for(int i=0;i<(n);++i)
#define Fr(i,n) for(int i=1;i<=(n);++i)
#define ifr(i,n) for(int i=(n)-1;i>=0;--i)
#define iFr(i,n) for(int i=(n);i>0;--i)

int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int n,k;
    cin>>n>>k;
    int a=((n-1)*(n-2))/2;
    if(k>a){
        cout<<-1<<endl;
        return 0;
    }
    cout<<n-1+a-k<<endl;
    Fr(i,n-1){
        cout<<i<<" "<<n<<endl;
    }
    int c=a-k;
    Fr(i,n-1){
        Fr(j,i-1){
            if(c==0) return 0;
            cout<<i<<" "<<j<<endl;
            --c;
        }
    }
}

Submission Info

Judge Result