#include<bits/stdc++.h>
using namespace std;
#define int long long
#define inf 5e18
#define nl '\n'
const int N = 1e5;
int ans[N], seg[4*N], lz[4*N], ix[4*N];
set<int> st;
int n;
void lazy(int l, int r, int p){
seg[p] += lz[p];
if(l != r){
lz[p*2] += lz[p];
lz[p*2+1] += lz[p];
}
lz[p] = 0;
}
void build(int l, int r, int p){
if(l == r){
if(l >= n) seg[p] = inf;
ix[p] = l;
return;
}
int m = (l+r)/2;
build(l, m, p*2);
build(m+1, r, p*2+1);
seg[p] = min(seg[p*2], seg[p*2+1]);
ix[p] = (seg[p*2] < seg[p*2+1] ? ix[p*2] : ix[p*2+1]);
}
void update(int l, int r, int p, int ql, int qr, int v){
lazy(l, r, p);
if(qr < l or r < ql) return;
if(ql <= l and r <= qr){
lz[p] += v;
lazy(l, r, p);
return;
}
int m = (l+r)/2;
update(l, m, p*2, ql, qr, v);
update(m+1, r, p*2+1, ql, qr, v);
seg[p] = min(seg[p*2], seg[p*2+1]);
ix[p] = (seg[p*2] < seg[p*2+1] ? ix[p*2] : ix[p*2+1]);
}
pair<int,int> query(int l, int r, int p, int ql, int qr){
lazy(l, r, p);
if(qr < l or r < ql) return {inf, -1};
if(ql <= l and r <= qr) return {seg[p], ix[p]};
int m = (l+r)/2;
auto [mn1, ix1] = query(l, m, p*2, ql, qr);
auto [mn2, ix2] = query(m+1, r, p*2+1, ql, qr);
return {min(mn1, mn2), (mn1 < mn2 ? ix1 : ix2)};
}
void upd(int ql, int qr, int v){
update(0, N-1, 1, ql, qr, v);
}
pair<int,int> qry(int ql, int qr){
return query(0, N-1, 1, ql, qr);
}
void impos(){
for(int i=0; i<n; i++) cout<<"-1 ";
exit(0);
}
void add(){
auto [mn, ix] = qry(0, n-1);
while(mn == 0){
st.insert(ix);
upd(ix, ix, inf);
auto [mn2, ix2] = qry(0, n-1);
mn = mn2;
ix = ix2;
}
}
inline void solve(){
int q;
cin>>n>>q;
build(0, N-1, 1);
vector<pair<int,int>> v[n];
while(q--){
int l, r, x;
cin>>l>>r>>x;
v[x].push_back({l, r});
upd(l, r, 1);
}
add();
for(int i=0; i<n; i++){
if(v[i].empty()){
if(st.empty()) impos();
auto it = st.begin();
ans[*it] = i;
st.erase(it);
continue;
}
int ml = 0, mr = inf;
for(auto [l, r] : v[i]){
upd(l, r, -1);
ml = max(ml, l);
mr = min(mr, r);
}
add();
auto it = st.lower_bound(ml);
if(it == st.end() or *it > mr) impos();
ans[*it] = i;
st.erase(it);
}
for(int i=0; i<n; i++) cout<<ans[i]<<" ";
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(NULL);cout.tie(NULL);
int t = 1;
//cin>>t;
while(t--) solve();
return 0;
}
