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#include <bits/stdc++.h>
using namespace std;
void __print(int x) { cerr << x; }
void __print(int64_t x) { cerr << x; }
void __print(uint32_t x) { cerr << x; }
void __print(uint64_t x) { cerr << x; }
void __print(float x) { cerr << x; }
void __print(double x) { cerr << x; }
void __print(long double x) { cerr << x; }
void __print(char x) { cerr << '\'' << x << '\''; }
void __print(const char *x) { cerr << '\"' << x << '\"'; }
void __print(const string &x) { cerr << '\"' << x << '\"'; }
void __print(bool x) { cerr << (x ? "true" : "false"); }
template<typename T, typename V>
void __print(const pair<T, V> &x) { cerr << '('; __print(x.first); cerr << ", "; __print(x.second); cerr << ')'; }
template<typename T>
void __print(const T &x) { int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}"; }
void _print() { cerr << "]\n"; }
template <typename T, typename... V>
void _print(T t, V... v) { __print(t); if (sizeof...(v)) cerr << ", "; _print(v...); }
#ifndef ONLINE_JUDGE1
#define debug(x...) cerr << " > [" << #x << "] = ["; _print(x)
#else
#define debug(x...)
#endif

int main() {
    ios_base::sync_with_stdio(false); cin.tie(nullptr);

    int n, m;
    cin >> n >> m;
    int a[n + 10][3];
    for(int i = 0; i <= n; i++) {
        a[i][0] = a[i][1] = a[i][2] = 0;
    }
    for(int i = 0; i < m; i++) {
        int l, r, c;
        cin >> l >> r >> c;
        l--; c--;
        a[l][c]++;
        a[r][c]--;
    }
    int res = 0;
    int cur[3] = {0, 0, 0};
    for(int i = 0; i < n; i++) {
        cur[0] += a[i][0];
        cur[1] += a[i][1];
        cur[2] += a[i][2];
        if(cur[2] == 0 and cur[1] > 0 and cur[0] > 0) res++;
    }
    cout << res;

    return 0;
}