#include <bits/stdc++.h> using namespace std; #define ll long long struct node{ int a, b; ll val; }; int main() { int n, k; cin>>n>>k; pair<ll, int> a[n]; bool bl=false; for(int i=0; i<n; i++){ cin>>a[i].first; a[i].second=i+1; if(i>0 && a[i]!=a[i-1]){ bl=true; } } if(bl){ int g; for(int i=1; i<=k; i++){ if(n%i==0 && k%i==0){ g=i; } } if((n*a[0].first)%k!=0){ cout<<-1; return 0; } cout<<n/g<<'\n'; for(int i=0; i<n/g; i++){ cout<<a[0].first*g/k<<" "; for(int j=0; j<k; j++){ cout<<(i*g+j)%n+1LL<<" "; } cout<<'\n'; } return 0; } if(n==2){ if(a[0].first==a[1].first){ cout<<a[0].first<<" "<<1<<" "<<2<<'\n'; }else{ cout<<-1<<'\n'; } return 0; } sort(a, a+n, [&](pair<int, int> x, pair<int, int> y){ return x.first<y.first; }); int sum=0; for(int i=0; i<n-1; i++){ sum+=a[i].first; } if(sum<a[n-1].first || (sum+a[n-1].first)%2==1){ cout<<-1; }else{ sum-=a[n-1].first; vector<node> v; while(sum>0){ if(sum>=2*a[n-3].first){ sum-=2*a[n-3].first; v.push_back({a[n-2].second, a[n-3].second, a[n-3].first}); a[n-2].first-=a[n-3].first; a[n-3].first=0; }else{ v.push_back({a[n-2].second, a[n-3].second, sum/2}); a[n-2].first-=sum/2; a[n-3].first-=sum/2; break; } for(int i=n-3; i>0; i--){ swap(a[i], a[i-1]); } for(int i=n-2; i>0; i--){ if(a[i].first>=a[i-1].first){ break; } swap(a[i], a[i-1]); } } for(int i=0; i<n-1; i++){ if(a[i].first>0){ v.push_back({a[n-1].second, a[i].second, a[i].first}); } } cout<<v.size()<<'\n'; for(auto& it : v){ cout<<it.val<<" "<<it.a<<" "<<it.b<<'\n'; } } }