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 <bits/stdc++.h>
using namespace std;
#define IOS ios::sync_with_stdio(false); cin.tie(0);
#define FOR(i,s,n) for(int i = s; i < (n); i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(n) (n).begin(), (n).end()
#define RALL(n) (n).rbegin(), (n).rend()
#define ATYN(n) cout << ( (n) ? "Yes":"No") << endl;
#define CFYN(n) cout << ( (n) ? "YES":"NO") << endl;
#define OUT(n) cout << (n) << endl;
using ll = long long;
using ull = unsigned long long;
using pii = pair<int,int>;

int main(void)
{
    IOS
    while(true) {
        int n, m;
        cin >> n >> m;
        if (n == 0) break;
        vector<vector<pii>> utime(m);
        vector<int> pcount(m);
        int r; cin >> r;
        REP(i,r) {
            int t,p,s,l;
            cin >> t >> p >> s >> l;
            s--;
            if (l == 1) {
                if (pcount[s] == 0) utime[s].push_back({t,0});
                pcount[s]++;
            } else {
                if (pcount[s] == 1) utime[s].back().second = t;
                pcount[s]--;
            }
        }

        int q; cin >> q;
        REP(i,q) {
            int s, e, st;
            cin >> s >> e >> st;
            st--;
            int ans = 0;
            for(auto p:utime[st]) {
                int s2 = s < p.first ? p.first : s;
                int e2 = e > p.second ? p.second : e;
                ans += max(0,e2 - s2);
            }
            cout << ans << endl;
        }
    }

    return 0;
}

C++: #include <iostream>
using std::cin;
using std::cout;
using std::endl;
#include <algorithm>
using std::pair;
using std::make_pair;
#include <vector>
using std::vector;

#define MAX_T 1260

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
        cin >> n >> m;
        if (n == 0 && m == 0) {
            break;
        }

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

        VP time(m + 1);

        int r;
        cin >> r;
        for (int i = 0; i < r; i++) {
            int t;
            int n2; // pc
            int m2; // person
            int s;
            cin >> 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;
        cin >> q;
        for (int i = 0; i < q; i++) {
            int s;
            int e;
            int m2;
            cin >> 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 (first < s) {
                    start = s;
                } else if (first <= e) {
                    start = first;
                } else {
                    continue;
                }
                if (second < s) {
                    break;
                } else if (second <= e) {
                    end = second;
                } else {
                    end = e;
                }
                count += end - start;
            }
            cout << count << endl;
        }

    }
    return 0;
}

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


int main()
{
	int N,M;
	while(cin>>N>>M && N!=0){
		vector<int> PC(N+1,-1);
		vector<vector<pair<int,int> > > 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(make_pair(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(Stu[m][k].second<time) continue;
				ans+=min(Stu[m][k].second,e)-max(time,Stu[m][k].first);
				time=min(Stu[m][k].second,e);
			}
			cout<<ans<<endl;
		}
	}
}