Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func main() {
	io := NewIo()
	defer io.Flush()
	for {
		_, M := io.NextInt(), io.NextInt()
		if M == 0 {
			break
		}
		r := io.NextInt()
		t, m, s := make([]int, r), make([]int, r), make([]int, r)
		for i := 0; i < r; i++ {
			t[i], _, m[i], s[i] = io.NextInt(), io.NextInt(), io.NextInt()-1, io.NextInt()
		}
		q := io.NextInt()
		for i := 0; i < q; i++ {
			ss, ee, mm := io.NextInt(), io.NextInt(), io.NextInt()-1
			x := make([]int, 1300)
			for j := 0; j < r; j++ {
				if m[j] == mm {
					if s[j] == 1 {
						x[t[j]]++
					} else {
						x[t[j]]--
					}
				}
			}
			for j := 1; j < 1300; j++ {
				x[j] = x[j] + x[j-1]
			}
			ans := 0
			for j := ss; j < ee; j++ {
				if x[j] > 0 {
					ans++
				}
			}
			io.Println(ans)
		}
	}
}

// I/O template
type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

func (io *Io) Flush() {
	err := io.writer.Flush()
	if err != nil {
		panic(err)
	}
}

func (io *Io) NextLine() string {
	var buff []byte
	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buff = append(buff, line...)
		if !isPrefix {
			break
		}
	}
	return string(buff)
}

func (io *Io) Next() string {
	for io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}
	s := io.tokens[io.nextToken]
	io.nextToken++
	return s
}

func (io *Io) NextInt() int {
	i, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) NextFloat() float64 {
	i, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) Println(a ...interface{}) {
	fmt.Fprintln(io.writer, a...)
}

func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

func (io *Io) PrintIntSlice(a []int) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func (io *Io) PrintStringSlice(a []string) {
	b := []interface{}{}
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func Log(name string, value interface{}) {
	fmt.Fprintf(os.Stderr, "%s=%+v\n", name, value)
}

func ExampleIo() {
	io := NewIo()
	defer io.Flush()
	a := make([]int, 0, 3)
	a[0], a[1], a[2] = io.NextInt(), io.NextInt(), io.NextInt()
	io.Println(a)
	io.PrintIntSlice(a)
	Log("io", a)
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

class hist{
public:
	int s,e;
	hist(int s,int e):s(s),e(e){};
};

bool operator < (hist a,hist b){
	if(a.s!=b.s) return a.s<b.s;
	return a.e<b.e;
}

int main()
{
	int N,M;
	while(cin>>N>>M && N!=0){
		vector<int> PC(N+1,-1);
		vector<vector<hist> > Stu(M+1);
		int r;
		cin>>r;
		for(int i=0;i<r;i++){
			int t,n,m,s;
			cin>>t>>n>>m>>s;
			if(s==0)
				Stu[m].push_back(hist(PC[n],t));
			else{
				PC[n]=t;
			}
		}
		int q;
		cin>>q;
		for(int i=0;i<q;i++){
			int s,e,m;
			cin>>s>>e>>m;
			sort(Stu[m].begin(),Stu[m].end());
			int ans=0;
			int time=s;
			for(int k=0;k<Stu[m].size();k++){
				if(min(Stu[m][k].e,e)-max(time,Stu[m][k].s)<0) continue;
				ans+=min(Stu[m][k].e,e)-max(time,Stu[m][k].s);
				time=min(Stu[m][k].e,e);
			}
			cout<<ans<<endl;
		}
	}
}

C++: #include <iostream>
#include <sstream>
#include <fstream>
#include <string>
#include <vector>
#include <deque>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <algorithm>
#include <functional>
#include <utility>
#include <bitset>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cstdio> 
#include <cstring>

#define rep(i, n) for(int (i) = 0; (i) < (n); (i)++)
#define rangeRep(i, n, m) for(int (i) = (n); (i) < (m); (i)++)
struct Student {
	int t, n, m, s;
};

constexpr int timeOffset = 540;
//[PC][??????] = ????????????
int dp[1000][1260 - timeOffset] = { 0 };


class Solve {
public:
	Solve() {};
	~Solve() {};

	void solver() {
		std::vector<std::vector<int>> results;
		while (1) {
			int n, m, r, q;
			std::vector<Student> students;
			std::cin >> n >> m;
			if (!n) break;

			std::memset(dp, 0, 1000 * (1260 - timeOffset) * sizeof(int));
			long long a = 1000 * (1260 - timeOffset) * sizeof(int);
			results.push_back(std::vector<int>());
			//?????°???????????±
			std::cin >> r;
			Student s;
			rep(i, r) {
				//??????, PC??????, ????????????, isLogin
				std::cin >> s.t >> s.n >> s.m >> s.s;
				//?????°??????
				if (s.s) {
					//?????°??????????§???????????????????
					dp[s.n - 1][s.t - timeOffset] = s.m;
				}//?????°??¢??????
				else {
					//?????°????????¨????????§?????£?????????
					int time = s.t - timeOffset - 1;
					while (dp[s.n - 1][time] == 0) {
						dp[s.n - 1][time--] = s.m;
					} 
				}
			}

			//?????? [ts, te]??????????????????m????????¨??????
			std::cin >> q;
			rep(i, q) {
				int num = 0;
				int ts, te, m;
				std::cin >> ts >> te >> m;
				ts -= timeOffset; te -= timeOffset;
				//???????????????PC??§?????°?????????????????????????????????
				rangeRep(j, ts, te) {
					rep(k, 1000) {
						if (dp[k][j] == m) {
							num++;
							break;
						}
					}
				}
				results.back().push_back(num);
			}
		}

		for (auto& x : results) {
			for (auto& y : x) {
				std::cout << y << std::endl;
			}
		}
	}
private:

};

int main() {
	Solve solve;
	solve.solver();
	return 0;
}

C++: #include<iostream>
#include<cstring>
using namespace std;

int S[100][1261]={};

int main()
{
  int N,M,r,q,t,n,m,s,ts,te,time;

  while(1){
    cin>>N>>M;
    if(N==0 && M==0)break;
    for(int i=0;i<M;i++){
      for(int j=0;j<=1261;j++)S[i][j]=0;
    }
    cin>>r;
    for(int i=0;i<r;i++){
      cin>>t>>n>>m>>s;
      if(s==1)S[m-1][t]=1;
      else S[m-1][t]=-1;
    }
    for(int i=0;i<M;i++){
      for(int j=1;j<=1261;j++){
        S[i][j]+=S[i][j-1];
      }
    }
    cin>>q;
    for(int i=0;i<q;i++){
      cin>>ts>>te>>m;
      time=0;
      for(int j=ts;j<te;j++){
	if(S[m-1][j]>0)time++;
      }
      cout<<time<<endl;
    }
  }
  return 0;
}