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 <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++;
          time--;
        }
        if (time == et) {
          if (cnt > 0) {
            ut += et-st_tmp;
          }
          break;
        }
      }
      cout << ut << el;
    }
  }
}

C++: #include <bits/stdc++.h>
 
using namespace std;
typedef long long ll;
 
#define rep(i, n) for(int i=0; i<(n); ++i)

class history {
public:
    int pc, start, end;
    history(int p, int s, int e) {
        pc = p; start = s; end = e;
    }
};
vector<history> hist[10001];
int main(void){
    int N, M;
    int r, t, n, m, s, ts, te, q;
    while(cin >> N >> M && N) {
        rep(i, 1001) hist[i].clear();
        cin >> r;
        rep(i, r) {
            cin >> t >> n >> m >> s;
            n--; m--;
            if(s==1) {
                hist[m].push_back(history(n, t, -1));
            } else {
                rep(j, hist[m].size()) {
                    if(hist[m][j].pc == n && hist[m][j].end == -1) {
                        hist[m][j].end = t;
                        break;
                    }
                }
            }
        }
        cin >> q;
        rep(i, q) {
            int ans = 0;
            cin >> ts >> te >> m;
            m--;
            int tmp[1265];
            rep(j, 1265) tmp[j] = 0;
            rep(j, hist[m].size()) {
                if(hist[m][j].end >= ts && hist[m][j].start <= te) {
                    for(int t=max(ts, hist[m][j].start); 
                            t <= min(te, hist[m][j].end); ++t) tmp[t] = 1;
                }
            }
            for(int j=540; j<1265; j++) {
                int state = 0;
                if(tmp[j] == 1) {
                    int start = j;
                    while(tmp[j]==1) j++;
                    ans += j - start - 1;
                }
            }
            cout << ans << endl;
        }
    }
}

C++: #include <iostream>
#define NUMBER 10000
#define TIME 1261
using namespace std;

int record[NUMBER][TIME];
int rec[1000][4];
int quest[50][3];

void answer_question(int q) {
  for (int i = 0; i < q; i++) {
    int student = quest[i][2];
    int count = 0;
    for (int j = quest[i][0]; j <= quest[i][1]; j++) {
      int t = -1;
      if (record[student][j]) {
	for (int k = j; k <= quest[i][1]; k++) {
	  if (record[student][k] == 0) {
	    t = k - 1;
	    break;
	  }
	  if (k == quest[i][1]) t = k;
	}
	count += t - j;
	j = t;
      }
    }
    cout << count << endl;
  }
}

void record_search(int r) {
  for (int i = 0; i < r; i++) {
    if (rec[i][3] == 0) continue;
    for (int j = i + 1; j < r; j++) {
      if (rec[j][1] == rec[i][1] && rec[j][2] == rec[i][2] && rec[j][3] == 0) {
	for (int k = rec[i][0]; k <= rec[j][0]; k++) {
	  record[rec[i][2]][k] = 1;
	}
	goto label;
      }
    }
  label: ;
  }
}

int main() {
  while (true) {
    int n, m;
    cin >> n >> m;
    if (n == 0 && m == 0) return 0;

    int r, q;
    cin >> r;
    for (int i = 0; i < r; i++)
      cin >> rec[i][0] >> rec[i][1] >> rec[i][2] >> rec[i][3];

    cin >> q;
    for (int i = 0; i < q; i++)
      cin >> quest[i][0] >> quest[i][1] >> quest[i][2];

    for (int i = 0; i < r; i++)
      for (int j = 0; j < TIME; j++)
	record[i][j] = 0;
    record_search(r);
    answer_question(q);
  }
}