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// Karol Kosinski 2020
#include <cstdio>
#include <algorithm>
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
//#define DEBUG(x...) printf(x)
#define DEBUG(x...)
using namespace std;

const int NX = 1'000'001;

struct I { int left, right; };
bool operator < (const I& a, const I& b) { return a.left - b.left < 0; }

bool cans[NX];
int ends[3];
I intervals[3][NX];

void choose(int n, int ind, bool filler)
{
    int e = ends[ind], ci = 0;
    FOR(j,0,e)
    {
        const auto& val = intervals[ind][j];
        while (ci < val.left)
        {
            cans[ci] = cans[ci] and not filler;
            ++ ci;
        }
        while (ci <= val.right)
        {
            cans[ci] = cans[ci] and filler;
            ++ ci;
        }
    }
    while (ci < n)
    {
        cans[ci] = cans[ci] and not filler;
        ++ ci;
    }
}

int main()
{
    int n, m, res = 0;
    scanf("%d%d", &n, &m);
    fill(cans, cans + n, true);
    FOR(i,0,m)
    {
        int l, r, k;
        scanf("%d%d%d", &l, &r, &k);
        -- k;
        intervals[ k ][ ends[k] ++ ] = (I) { l - 1, r - 1 };
    }
    FOR(i,0,3)
    {
        sort(&intervals[i][0], &intervals[i][ends[i]]);
    }
    choose(n, 2, false);
    choose(n, 1, true);
    choose(n, 0, true);
    FOR(i,0,n) if (cans[i])
    {
        DEBUG("%d ", i);
        ++ res;
    }
    DEBUG("\n");
    printf("%d\n", res);
    return 0;
}