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 <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][time] = Student
int use[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(use, 0, sizeof(use));
			results.push_back(std::vector<int>());
			//login info
			std::cin >> r;
			Student s;
			rep(i, r) {
				//time, PC, student, isLogin
				std::cin >> s.t >> s.n >> s.m >> s.s;
				//login
				if (s.s) {
					//set login start time
					use[s.n - 1][s.t - timeOffset] = s.m;
				}//logout
				else {
					//Fill until login start time
					int time = s.t - timeOffset - 1;
					while (use[s.n - 1][time] == 0) {
						use[s.n - 1][time--] = s.m;
					} 
				}
			}

			//question [ts, te]
			std::cin >> q;
			rep(i, q) {
				int num = 0;
				int ts, te, m;
				std::cin >> ts >> te >> m;
				ts -= timeOffset; te -= timeOffset;
				//Check if logged in on any PC.
				rangeRep(j, ts, te) {
					rep(k, n) {
						if (use[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>
using namespace std;

bool d[10010][1270];

int main() {

  long long int n, m, r, q, input_t, input_n, input_m, input_s;

  while( true ) {

    cin >> n >> m;

    if ( n == 0 ) break;

    cin >> r;

    for ( long long int i = 0; i < 10010; i++ ) {
      for ( long long int j = 0; j < 1270; j++ ) {
	d[i][j] = false;
      }
    }
    long long int pc[1010] = {0};
    for ( long long int i = 0; i < r; i++ ) {
      cin >> input_t >> input_n >> input_m >> input_s;
      if ( pc[input_n] == 0 ) {
	pc[input_n] = input_t;
      }else {
	for ( long long int i = pc[input_n]; i < input_t; i++ ) {
	  d[input_m][i] = true;
	}
	pc[input_n] = 0;
      }
    }
    cin >> q;
    for ( long long int i = 0; i < q; i++ ) {
      cin >> input_t >> input_s >> input_m;
      long long int ans = 0;
      for ( long long int j = input_t; j < input_s; j++ ) {
	if ( d[input_m][j] ) ans++;
      }
      cout << ans << endl;
    }

  }

  return 0;

}

C++: #include <algorithm>
#include <iostream>
#include <limits.h>
#include <math.h>
#include <set>
#include <stack>
#include <stdlib.h>
#include <string>
#include <vector>

#define el endl
#define fd fixed
#define INF INT_MAX/2-1
#define pb push_back

using namespace std;

class Record
{
public:
  int t;
  int n;
  int m;
  int s;
};

int main() {
  int N, M, r, t, n, m, s, q, st, et, st_tmp;
  while (cin >> N >> M, N | M) {
    cin >> r;
    Record records[r];
    for (int i = 0; i < r; i++) {
      cin >> t >> n >> m >> s;
      records[i].t = t;
      records[i].n = n;
      records[i].m = m;
      records[i].s = s;
    }
    cin >> q;
    while (q--) {
      cin >> st >> et >> m;
      int i = 0, cnt = 0, ut = 0;
      for (int time = 540; time <= 1260; time++) {
        if (records[i].t == time) {
          if (records[i].m == m) {
            if (records[i].s) {
              if (cnt == 0) {
                if (time < st) {
                  st_tmp = st;
                } else if (et <= time) {
                  continue;
                } else {
                  st_tmp = time;
                }
              }
              cnt++;
            } else {
              cnt--;
              if (cnt == 0) {
                if (time <= st) {
                  continue;
                } else {
                  ut += time - st_tmp;
                }
              }
            }
          }
          i++;
        }
        if (time == et) {
          if (cnt > 0) {
            ut += et-st_tmp;
          }
          break;
        }
      }
      cout << ut << el;
    }
  }
}