#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#define rep(i, s, e) for (ll i = s; i < e; i++)
#define upmax(a, b) a = max(a, b)
#define upmin(a, b) a = min(a, b)
using namespace std;
using ll = long long;
using vll = vector<ll>;
using vvll = vector<vll>;
using pll = pair<ll, ll>;
using vpll = vector<pll>;
using vvpll = vector<vpll>;
const ll INF = 1e18;
struct tr {
ll l, r;
ll lazy_val = -1;
tr* lp = nullptr, * rp = nullptr;
tr(ll l, ll r) : l(l), r(r) {
if (l == r - 1) {
return;
}
lp = new tr(l, (l + r) / 2);
rp = new tr((l + r) / 2, r);
}
void push() {
if (lazy_val == -1) return;
upmax(lp->lazy_val, lazy_val);
upmax(rp->lazy_val, lazy_val);
lazy_val = -1;
}
// Update the range [f,t) to val
void update(ll f, ll t, ll val) {
if (f >= r || t <= l) return;
if (l >= f && r <= t) {
lazy_val = val;
return;
}
push();
lp->update(f, t, val);
rp->update(f, t, val);
}
ll query(ll idx) {
if (idx >= r || idx < l) return -1;
if (l == r - 1) {
return lazy_val;
}
push();
ll v1 = lp->query(idx);
ll v2 = rp->query(idx);
if (v1 == -1) return v2;
return v1;
}
};
struct tr_min {
ll l, r;
ll min_val;
tr_min* lp = nullptr, * rp = nullptr;
tr_min(ll l, ll r, vll& arr) : l(l), r(r) {
if (l == r - 1) {
min_val = arr[l];
return;
}
lp = new tr_min(l, (l + r) / 2, arr);
rp = new tr_min((l + r) / 2, r, arr);
pull();
}
void pull() {
min_val = min(lp->min_val, rp->min_val);
}
// Query the segment [f,t)
ll query(ll f, ll t) {
if (l >= t || r <= f) return INF;
if (l >= f && r <= t) return min_val;
return min(lp->query(f, t), rp->query(f, t));
}
};
void solve() {
ll n, q;
cin >> n >> q;
vector<pair<ll, pll>> queries(q);
vll maxL(n, -1), minR(n, INF);
rep(i, 0, q) {
ll l, r, a;
cin >> l >> r >> a;
queries[i] = { a, {l, r} };
upmax(maxL[a], l);
upmin(minR[a], r);
}
tr seg(0, n);
/*rep(i, 0, n) {
if (maxL[i] > minR[i]) {
rep(j, 0, n) cout << -1 << ' ';
cout << endl;
return;
}
//cout << maxL[i] << ' ' << minR[i] << endl;
//if (minR[i] != INF && maxL[i] != -1) seg.update(maxL[i], minR[i] + 1, i);
}*/
sort(queries.begin(), queries.end());
rep(i, 0, q) {
seg.update(queries[i].second.first, queries[i].second.second + 1, queries[i].first);
}
vll ans(n);
rep(i, 0, n) {
ans[i] = seg.query(i);
if (ans[i] == -1) ans[i] = n;
//cout << ans[i] << ' ';
}
//cout << endl;
tr_min seg2(0, n, ans);
rep(i, 0, q) {
ll l = queries[i].second.first;
ll r = queries[i].second.second;
ll a = queries[i].first;
ll v = seg2.query(l, r + 1);
if (v != a) {
rep(j, 0, n) cout << "-1 ";
cout << endl;
return;
}
}
rep(i, 0, n) cout << ans[i] << ' ';
cout << endl;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
solve();
}
