#include<bits/stdc++.h>
using namespace std;
#define int long long
#define fall(i,a,b) for(int i=a;i<=b;i++)
#define rfall(i,a,b) for(int i=a;i>=b;i--)
#define pb push_back
#define F first
#define all(x) x.begin(),x.end()
#define S second
#define sz(x) (int)x.size()
const int MAXN=5e2+10;
typedef pair<int,int> pii;
typedef tuple<int,int,int> trio;
int c[MAXN][MAXN],n,b[MAXN][MAXN],W;
void show(vector<trio> arr){
cout<<sz(arr)<<"\n";
for(auto [u,j,k]:arr) cout<<u<<" "<<j<<" "<<k<<"\n";
}
int32_t main(){
std::ios_base::sync_with_stdio(false);
cin.tie(NULL);
cin>>n>>W;
fall(i,1,n-1)
fall(j,0,i-1) cin>>c[j][i],c[i][j]=c[j][i];
fall(i,1,n-1)
fall(j,0,i-1) cin>>b[j][i],b[i][j]=b[j][i];
if(c[0][1]+b[0][1]<W){
cout<<"NO\n";
return 0;
}
vector<trio> roads;
fall(i,0,n-2) roads.pb({i,i+1,W-c[0][1]});
fall(i,0,n-2) roads.pb({i,i+1,b[0][1]});
show(roads);
}
