#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,B,pai[MAXN],dp[MAXN];
vector<trio> roads;
vector<pii> g[MAXN],g1[MAXN];
bool ok=1;
void show(vector<trio> arr){
cout<<sz(arr)<<"\n";
for(auto [u,j,k]:arr) cout<<u<<" "<<j<<" "<<k<<"\n";
}
int find(int x){
return x==pai[x]?x:pai[x]=find(pai[x]);
}
void merge(int a,int b){
a=find(a),b=find(b);
pai[a]=b;
}
void build_KRT(){
vector<trio> ord;
fall(i,0,n-1)
fall(j,i+1,n-1) ord.pb({c[i][j],i,j});
fall(i,0,n-1) pai[i]=i;
sort(all(ord),greater<>());
for(auto [w,a,b]:ord){
if(find(a)==find(b)) continue;
merge(a,b);
g[a].pb({b,w}); g[b].pb({a,w});
roads.pb({a,b,W-w});
}
}
void build_KRT2(){
vector<trio> ord;
fall(i,0,n-1)
fall(j,i+1,n-1) ord.pb({b[i][j],i,j});
fall(i,0,n-1) pai[i]=i;
sort(all(ord),greater<>());
for(auto [w,a,b]:ord){
if(find(a)==find(b)) continue;
merge(a,b);
g1[a].pb({b,w}); g1[b].pb({a,w});
roads.pb({a,b,w});
}
}
void bfs1(int x){
fall(i,0,n-1) dp[i]=-1;
dp[x]=W+10;
priority_queue<pii> pq; pq.push({dp[x],x});
while(!pq.empty()){
auto [d,a]=pq.top(); pq.pop();
if(d!=dp[a]) continue;
if(a!=x) ok&=(c[a][x]==dp[a]);
for(auto [u,w]:g[a]){
if(dp[u]<min(dp[a],w)){
dp[u]=min(dp[a],w);
pq.push({dp[u],u});
}
}
for(auto [u,w]:g1[a]){
if(dp[u]<min(dp[a],w)){
dp[u]=min(dp[a],w);
pq.push({dp[u],u});
}
}
}
fall(i,0,n-1) if(dp[i]==-1) ok=0;
}
void bfs2(int x){
fall(i,0,n-1) dp[i]=-1;
dp[x]=W+10;
priority_queue<pii> pq; pq.push({dp[x],x});
while(!pq.empty()){
auto [d,a]=pq.top(); pq.pop();
if(d!=dp[a]) continue;
if(a!=x) ok&=(b[a][x]==dp[a]);
for(auto [u,w]:g[a]){
if(dp[u]<min(dp[a],w)){
dp[u]=min(dp[a],w);
pq.push({dp[u],u});
}
}
for(auto [u,w]:g1[a]){
if(dp[u]<min(dp[a],w)){
dp[u]=min(dp[a],w);
pq.push({dp[u],u});
}
}
}
fall(i,0,n-1) if(dp[i]==-1) ok=0;
}
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];
}
fall(i,1,n-1){
fall(j,0,i-1){
if(c[i][j]+b[i][j]>=W){
g[i].pb({j,c[i][j]}); g[j].pb({i,c[i][j]});
roads.pb({i,j,W-c[i][j]});
g1[i].pb({j,b[i][j]}); g1[j].pb({i,b[i][j]});
roads.pb({i,j,b[i][j]});
}
}
}
fall(i,0,n-1)
for(auto &[u,w]:g1[i]) w=W-w;
fall(i,0,n-1){
bfs1(i);
}
fall(i,0,n-1)
for(auto &[u,w]:g1[i]) w=W-w;
fall(i,0,n-1)
for(auto &[u,w]:g[i]) w=W-w;
fall(i,0,n-1) bfs2(i);
if(!ok){
cout<<"NO\n";
return 0;
}
show(roads);
}
