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 <utility>

using namespace std;

int main(void)
{
  while (true) {
    int n, m;
    cin >> n >> m;
    if (n == 0 && m == 0) break;
    int r;
    cin >> r;
    int time[r], pc[r], stu[r], log[r];
    for (size_t i = 0; i < r; i++) {
      cin >> time[i] >> pc[i] >> stu[i] >> log[i];   
    }
    int que;
    cin >> que;
    int ts[que], te[que], qm[que];
    for (size_t i = 0; i < que; i++) {
      cin >> ts[i] >> te[i] >> qm[i];
    }
    //??\??????

    //question
    for (size_t k = 0; k < que; k++) {

      vector<int> accep;
      for (size_t i = 0; i < r; i++) {
	if (stu[i] == qm[k]) {
	  accep.push_back(i);
	}
      }

      int tl[accep.size()]; //time log
      int ll[accep.size()]; //loginout log
      int pl[accep.size()]; //pc log
      
      for (size_t i = 0; i < accep.size(); i++) {
	tl[i] = time[accep[i]];
	ll[i] = log[accep[i]];
	pl[i] = pc[accep[i]];
      }

      int diff = te[k] - ts[k];
      vector<int> timecount;
      timecount.resize(diff);
      for (size_t i = 0; i < diff; i++)
	timecount[i] = 0;
      
      for (size_t i = 0; i < accep.size(); i++) {
	int start, end;
	
	//?????°??????
	if (ll[i]) { 
	  if (tl[i] < te[k]) {
	    start = tl[i];
	    
	    int pcnum = pl[i];
	    int j = i;
	    while (true) {
	      //?????°????????????PC???????????????????????°??¢??????
	      if (pl[j] == pcnum && ll[j] == 0) {
		end = tl[j];
		//?????°?????????ts???????????????
		if (start < ts[k]) {
		  start = ts[k];
		} start = start - ts[k];
		//?????°??¢?????????te???????????????
		
		if (te[k] < end) {
		  end = te[k];
		} end = end -  ts[k];

		for (size_t l = start; l < end; l++)
		  timecount[l] = 1;
		break;
	      }
	      j++;
	    }
	  }
	}

      }
      int cnt = 0;
      for (size_t i = 0; i < diff; i++)
	if (timecount[i])
	  cnt++;
      cout << cnt << endl;
    }
  }
  
  return true;
}

C++: #include<bits/stdc++.h>
using namespace std;

int main(){
while(1){//start


	int N, M, r;
	//N；PC数　M；学生数
	cin >> N >> M;
	if(N == 0 and M == 0) break;
	cin >> r;


	//学生数、　時間
	int data[10004][721];
	for(int j = 0; j < 10004; j++){
		for(int k = 0; k < 721; k++) data[j][k] = 0;
	}


	for(int i = 0; i < r; i++){
		// t；時刻、　n;PC番号　m；学生番号　s；１ならログイン、０ならログアウト(配列中では逆)
		int t, n, m;
		bool s;
		cin >> t >> n >> m >> s;
		if(s) data[m][t - 539] += 1;
		else data[m][t - 539] += -1;
	}

	//累積和をとる
	for(int i = 0; i <= M; i++){
		for(int k = 1; k < 721; k++) data[i][k] = data[i][k] + data[i][k - 1];
	}


	//クエリを取得
	int qn;
	cin >> qn;
	for(int i = 0; i < qn; i++){
		int ts, tt, sn;
		cin >> ts >> tt >> sn;

		//学生について調査する
		int ans = 0;
		for(int j = ts - 539; j < tt - 539; j++){
			if(data[sn][j]) ans++;
		}
		cout << ans << endl;
	}

}//end

	return 0;
}

C++: #include <iostream>
#include <cstdio>
#include <algorithm>
using std::pair;
using std::make_pair;
#include <vector>
using std::vector;

typedef vector<int> VI;
typedef pair<int, int> PII;
typedef vector<vector<PII> > VP;

int main(void) {
    while (1) {
        int n; // pc
        int m; // person
        scanf("%d%d", &n, &m);
        if (n == 0 && m == 0) {
            break;
        }

        VI pc(m + 1, 0);
        VI start(m + 1, 0);

        VP time(m + 1);

        int r;
        scanf("%d", &r);
        for (int i = 0; i < r; i++) {
            int t;
            int n2; // pc
            int m2; // person
            int s;
            scanf("%d%d%d%d", &t, &n2, &m2, &s);
            if (s == 1) {
                if (pc[m2] == 0) {
                    start[m2] = t;
                }
                pc[m2]++;
            } else {
                pc[m2]--;
                if (pc[m2] == 0) {
                    int end = t;
                    time[m2].push_back(make_pair(start[m2], end));
                }
            }
        }

        int q;
        scanf("%d", &q);
        for (int i = 0; i < q; i++) {
            int s;
            int e;
            int m2;
            scanf("%d%d%d", &s, &e, &m2);
            int count = 0;

            for (int j = 0; j < (int)(time[m2].size()); j++) {
                int first = time[m2][j].first;
                int second = time[m2][j].second;
                int start;
                int end;
                if (s < first) {
                    start = first;
                } else if (s <= second) {
                    start = s;
                } else {
                    continue;
                }
                if (e < first) {
                    break;
                } else if (e <= second) {
                    end = e;
                } else {
                    end = second;
                }
                count += end - start;
            }
            printf("%d\n", count);
        }

    }
    return 0;
}