#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define f first
#define s second
#define sz(a) ((int)(a).size())
#define all(a) (a).begin(), (a).end()
#define uni(a) sort(all(a)), (a).resize(unique(all(a)) - (a).begin())
typedef pair <int, int> ii;
const int N = 1e5 + 10;
int n, q, ans[N], lz[N << 2], t[N];
multiset <int> pos;
vector <int> fp, fv;
vector <ii> s[N];
void upd(int l, int r, int id, int u, int v, int x) {
if (l > v || r < u) return;
if (l >= u && r <= v) {
lz[id] = min(lz[id], x);
return;
}
int mid = (l + r) >> 1;
upd(l, mid, id << 1, u, v, x);
upd(mid + 1, r, id << 1 | 1, u, v, x);
}
int get(int x) {
int l = 0, r = n - 1, id = 1, ans = 1e9;
while (l < r) {
int mid = (l + r) >> 1;
ans = min(ans, lz[id]);
if (x <= mid) {
id = id << 1;
r = mid;
} else {
id = id << 1 | 1;
l = mid + 1;
}
}
return ans;
}
void solve() {
cin >> n >> q;
memset(lz, 0x3f, sizeof(lz));
for (int i = 1; i <= q; i++) {
int l, r, x;
cin >> l >> r >> x;
upd(0, n - 1, 1, l, r, x);
s[x].push_back({l, r});
}
for (int i = 0; i < n; i++) {
t[i] = get(i); pos.insert(i);
if (t[i] >= 1e9) {
t[i] = -1;
}
ans[i] = -1;
}
bool found = 1;
for (int i = n - 1; i >= 0; i--) {
if (sz(s[i]) == 0)
continue;
int x = s[i][0].f, y = s[i][0].s;
for (auto v : s[i]) {
x = max(x, v.f), y = min(y, v.s);
}
if (x <= y) {
auto it = pos.lower_bound(x);
if (it == pos.end() || *it > y) {
found = 0;
break;
}
ans[*it] = i;
pos.erase(it);
}
for (auto x : s[i]) {
for (auto it = pos.lower_bound(x.f); it != pos.end() && *it <= x.s; )
it = pos.erase(it);
}
}
for (int i = 0; i < n; i++) {
if (ans[i] == -1) {
fp.push_back(i);
}
if (!sz(s[i])) {
fv.push_back(i);
}
}
sort(all(fp), [&](int x, int y){return t[x] < t[y];});
sort(all(fv));
for (int i = 0; i < sz(fv); i++) {
if (t[fp[i]] > fv[i]) {
found = 0;
break;
}
ans[fp[i]] = fv[i];
}
if (found) {
for (int i = 0; i < n; i++) {
cout << ans[i] << ' ';
}
cout << '\n';
} else {
for (int i = 0; i < n; i++) {
cout << -1 << ' ';
}
cout << '\n';
}
}
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
// freopen("a.inp", "r", stdin);
// freopen("a.out", "w", stdout);
int t = 1;
// cin >> t;
while (t--) {
solve();
}
return 0;
}
