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#include <cstdio>
#include <cstring>
#include <cmath>
#include <cassert>
#include <iostream>
#include <algorithm>
#include <iterator>
#include <string>
#include <vector>
#include <queue>
#include <bitset>
#include <utility>
#include <stack>

using namespace std;
typedef long long LL;
typedef pair<int,int> PII;
typedef vector<int> VI;
#define MP make_pair
#define FOR(v,p,k) for(int v=(p);v<=(k);++v)
#define FORD(v,p,k) for(int v=(p);v>=(k);--v)
#define REP(i,n) for(int i=0;i<(n);++i)
#define VAR(v,i) __typeof(i) v=(i)
#define FOREACH(i,c) for(VAR(i,(c).begin());i!=(c).end();++i)
#define PB push_back
#define ST first
#define ND second
#define SIZE(x) (int)x.size()
#define ALL(c) c.begin(),c.end()

#define ODD(x) ((x)%2)
#define EVEN(x) (!(ODD(x)))


int main() {
    int n, m;
    scanf("%d%d\n", &n, &m);
    int res = 0;
    vector<pair<int, PII>> t;
    t.reserve(2*m+1);
    REP(i, m) {
        int l, r, k;
        scanf("%d%d%d", &l, &r, &k);
        t.PB(MP(l, MP(0, k)));
        t.PB(MP(r, MP(1, k)));
    }
    t.PB(MP(n+1, MP(0, 3)));
    sort(begin(t), end(t));

    VI prev_color(4), color(4);
    int prev_pos = 0;
    auto is_green = [](auto &color){ return color[1] > 0 && color[2] > 0 && color[3] == 0; };
    
    for(auto &tt : t) {
        int pos = tt.ST;
        int is_end = tt.ND.ST;
        int k = tt.ND.ND;

        if (prev_pos < pos) {
            if (is_green(prev_color)) {
                res += 1;
            }
            if (is_green(color)) {
                res += pos-prev_pos-1;
            }
            prev_pos = pos;
            prev_color = color;
        }
        if (is_end) {
            color[k]--;
        } else {
            color[k]++;
            prev_color[k]++;
        }
    }

    printf("%d\n", res);
    return 0;
}