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#include <bits/stdc++.h>

using namespace std;

int col[1000002][3];

int main() {
    int n, m;
    scanf("%d%d", &n, &m);
    
    for (int i = 0; i < m; i++) {
        int a, b, k;
        scanf("%d%d%d", &a, &b, &k);
        k--;
        col[a][k]++;
        col[b+1][k]--;
    }
    
    for (int i = 1; i <= n; i++)
        for (int k = 0; k < 2; k++)
            col[i][k] += col[i - 1][k];
    
    int out = 0;
    for (int i = 1; i <= n; i++) {
        out += (col[i][0] > 0 && col[i][1] > 0 && col[i][2] == 0);
    }
    printf("%d\n", out);
}