C++ :

//神经网络
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <queue>
#include <cctype>

using namespace std;

const int N = 205;
struct Edge{
	int to,next,wei;
}edge[N * N];

struct Node{
	int c,u;
	Node (){
		c = 0; u = 0;
	}
}g[N];

int head[N],edgen = 0,rudu[N],n,p;
bool chudu[N];

inline int Read(){
	bool neg = false;
	char tmp = getchar();
	int rtn = 0;
	while (!isdigit(tmp)){
		if (tmp == '-') neg = true;
		tmp = getchar();
	}
	while (isdigit(tmp)){
		rtn = rtn * 10 + tmp - '0';
		tmp = getchar();
	}
	if (neg) rtn -= 2*rtn;
	return rtn;
}

inline void Add_Edge(int x,int y,int w){
	edge[edgen].to = y;
	edge[edgen].next = head[x];
	edge[edgen].wei = w;
	head[x] = edgen++;
}

void Rudu(){
	for (int i = 1;i <= n; i++)
		for (int p = head[i];p != -1;p = edge[p].next)	
			rudu[edge[p].to]++,chudu[i] = true;
}

int search(int k){
	if (!chudu[k]) return g[k].c;
	int rtn = 0;
	for (int p = head[k];p != -1;p = edge[p].next){
		int use = search(edge[p].to);
		if (use > 0)
			rtn += use * edge[p].wei;
	}
	rtn -= g[k].u;
	return rtn;
}

int main(){
	n = Read(),p = Read();
	for (int i = 1;i <= n; i++){
		g[i].c = Read();
		g[i].u = Read();
	}
	memset(head,-1,sizeof(head));
	for (int i = 1,x,y,w;i <= p; i++){
		x = Read();
		y = Read();
		w = Read();
		Add_Edge(y,x,w);
	}
	memset(rudu,0,sizeof(rudu));
	memset(chudu,false,sizeof(chudu));
	Rudu();
	bool flag = false;
	for (int i = 1;i <= n; i++)
		if (!rudu[i]){
			int use = search(i);
			if (use > 0){
				cout << i << " " << use << endl;
				flag = true;
			}
		}
	if (!flag) cout << "NULL\n";
	return 0;
}
/*
6 8
1 0
1 0
0 1
0 1
0 1
0 1
1 3 5
1 4 3
2 3 1
2 4 2
4 6 2
4 5 1
3 5 2
3 6 1
*/
/*
7 7
2 0
4 0
0 1
0 1
0 1
0 1
0 1
1 3 -2
1 4 1
3 6 -1
4 6 3
4 7 5
2 5 1
5 7 -1
*/

Pascal :

const
maxn=200;maxp=200;
var
i,j,n,p,maxlayer:integer;
w:array[0..maxp]of longint;
start,terminal:array[0..maxp]of byte;
u,c:array[0..maxn]of longint;
layer:array[0..maxn]of byte;
flag:boolean;
begin
readln(n,p);
for i:=1 to n do readln(c[i],u[i]);
fillchar(layer,sizeof(layer),0);
for i:=1 to p do begin
readln(start[i],terminal[i],w[i]);
layer[terminal[i]]:=layer[start[i]]+1;
end;
maxlayer:=layer[terminal[p]];
for i:=1 to n do
if layer[i]>0 then begin
for j:=1 to p do
if (terminal[j]=i)and(c[start[j]]>0)
then c[i]:=c[i]+w[j]*c[start[j]];
c[i]:=c[i]-u[i];
end;
flag:=true;
for i:=1 to n do
if (layer[i]=maxlayer) and (c[i]>0) then begin
writeln(i,' ',c[i]);
flag:=false;
end;
if flag then writeln('NULL');
end.