#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> ii;
#define fi first
#define se second
#define all(x) x.begin(), x.end()
#define sz(x) (int)(x.size())
#define MASK(i) (1ll << i)
const int N = 1e5 + 5;
int n, q, res[N];
bool b[N], f[N];
struct Qe {
int l, r, x;
}qry[N];
namespace sub1 {
bool check() {
return (n <= 10);
}
void solve() {
vector<int> v(n);
for (int i = 0; i < n; i++) v[i] = i;
do {
bool check = true;
for (int i = 1; i <= q; i++) {
int l = qry[i].l, r = qry[i].r, x = qry[i].x;
int mi = (int)1e9;
for (int j = l - 1; j < r; j++) {
mi = min(mi, v[j]);
}
if (mi != x) {
check = false;
break;
}
}
if (check) {
for (int i = 0; i < n; i++) cout << v[i] << " \n"[i == n - 1];
return;
}
}
while (next_permutation(all(v)));
for (int i = 1; i <= n; i++) cout << -1 << " \n"[i == n];
}
}
namespace sub2 {
bool check() {
return (n <= 1000 && q <= 1000);
}
bool b[N], f[N];
void solve() {
sort(qry + 1, qry + q + 1, [](Qe a, Qe b) { return a.x > b.x; });
vector<Qe> v;
for (int i = 1; i <= q; i++) {
int l = qry[i].l, r = qry[i].r, x = qry[i].x;
int cur = sz(v);
int k = l, h = l;
while (k <= r) {
while (b[k]) k++;
h = max(h, k);
while (h <= r && !b[h]) h++;
v.push_back({k, h - 1, x});
k = h;
}
if (sz(v) == cur) {
for (int i = 1; i <= n; i++) cout << -1 << " \n"[i == n];
return;
}
for (int j = l; j <= r; j++) b[j] = true;
}
for (int i = 1; i <= n; i++) res[i] = -1;
for (int i = 0; i < sz(v); i++) {
int l = v[i].l, r = v[i].r, x = v[i].x;
for (int j = l; j <= r; j++) res[j] = x;
f[x] = true;
}
vector<int> c;
for (int i = 0; i < n; i++) {
if (!f[i]) {
c.push_back(i);
}
f[i] = false;
}
int id = 0;
for (int i = 1; i <= n; i++) {
if (res[i] == -1) res[i] = c[id++];
}
for (int i = 1; i <= n; i++) {
if (f[res[i]] == true) {
if (c[id] > res[i]) res[i] = c[id++];
else {
for (int i = 1; i <= n; i++) cout << -1 << " \n"[i == n];
return;
}
}
f[res[i]] = true;
}
for (int i = 1; i <= n; i++) cout << res[i] << " \n"[i == n];
}
}
namespace sub3 {
int lab[N], mx[N];
void make_set() {
for (int i = 1; i <= n; i++) lab[i] = -1, mx[i] = i;
}
int find_(int u) { return lab[u] < 0 ? u : lab[u] = find_(lab[u]); }
void unite(int a, int b) {
a = find_(a), b = find_(b);
if (a == b) return;
if (lab[a] > lab[b]) swap(a, b);
mx[a] = max(mx[a], mx[b]);
lab[a] += lab[b];
lab[b] = a;
}
bool f[N];
void solve() {
sort(qry + 1, qry + q + 1, [](Qe a, Qe b) { return a.x > b.x; });
vector<Qe> v;
make_set();
for (int i = 1; i <= q; i++) {
int l = qry[i].l, r = qry[i].r, x = qry[i].x;
int cur = sz(v);
int k = l, h = l;
while (k <= r) {
int par = find_(k);
if (mx[par] != k) k = mx[par] + 1;
h = max(h, k);
if (h > r) break;
while (h <= r) {
int par = find_(h);
if (mx[par] == h) {
if (h - 1 >= l) unite(h, h - 1);
h++;
}
else break;
}
if (cur == sz(v)) {
for (int i = 1; i <= n; i++) cout << -1 << " \n"[i == n];
return;
}
v.push_back({k, h - 1, x});
}
}
for (int i = 1; i <= n; i++) res[i] = -1;
for (int i = 0; i < sz(v); i++) {
int l = v[i].l, r = v[i].r, x = v[i].x;
for (int j = l; j <= r; j++) res[j] = x;
f[x] = true;
}
vector<int> c;
for (int i = 0; i < n; i++) {
if (!f[i]) {
c.push_back(i);
}
f[i] = false;
}
int id = 0;
for (int i = 1; i <= n; i++) {
if (res[i] == -1) res[i] = c[id++];
}
for (int i = 1; i <= n; i++) {
if (f[res[i]] == true) {
if (c[id] > res[i]) res[i] = c[id++];
else {
for (int i = 1; i <= n; i++) cout << -1 << " \n"[i == n];
return;
}
}
f[res[i]] = true;
}
for (int i = 1; i <= n; i++) cout << res[i] << " \n"[i == n];
}
}
void solve() {
cin >> n >> q;
for (int i = 1; i <= q; i++) {
int l, r, val; cin >> l >> r >> val;
l++, r++;
qry[i] = {l, r, val};
}
// sub1::solve();
// sub2::solve();
// sub3::solve(); return;
if (sub1::check()) {
sub1::solve(); return;
}
else if (sub2::check()) {
sub2::solve(); return;
}
else {
sub3::solve();
}
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
// #define TASK "chonqua"
// freopen(TASK".inp", "r", stdin);
// freopen(TASK".out", "w", stdout);
int T = 1;
// cin >> T;
while (T--) {
solve();
}
}
