#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define pii pair <int , int>
#define arr3 array <int , 3>
/*
+ array limit ???
+ special case ??? n = 1?
+ time limit ???
*/
using namespace std;
const int INF = 1e9 + 7;
const int maxn = 1e5 + 7;
int n , q , mark[maxn] , ans[maxn];
arr3 query[maxn];
vector <pii> num[maxn];
bool check = 1;
void solve()
{
cin >> n >> q;
for(int i = 1; i <= q; i++)
{
cin >> query[i][0] >> query[i][1] >> query[i][2];
query[i][0]++; query[i][1]++; query[i][2]++;
num[query[i][2]].push_back({query[i][0] , query[i][1]});
}
set <int> uu , index; // unused
for(int i = 1; i <= n; i++)
{
uu.insert(i); index.insert(i);
}
index.insert(n+1);
vector <int> val;
for(int i = n; i >= 1; i--)
{
if(num[i].empty()) continue;
int limL = 0 , limR = n+1;
set <int> pos;
while(!uu.empty() && *uu.rbegin() >= i)
{
val.push_back(*uu.rbegin());
uu.erase(*uu.rbegin());
}
for(pii tmp: num[i])
{
int cur = *index.lower_bound(tmp.fi);
limL = max(limL , tmp.fi);
limR = min(limR , tmp.se);
while(cur <= tmp.se)
{
pos.insert(cur);
mark[cur] = i;
index.erase(cur);
cur = *index.upper_bound(cur);
}
}
if(limL > limR || *pos.lower_bound(limL) > limR || pos.size() > val.size())
{
check = false; break;
}
ans[*pos.lower_bound(limL)] = i;
pos.erase(pos.lower_bound(limL));
val.pop_back();
for(int p: pos)
{
ans[p] = val.back();
val.pop_back();
}
}
if(!check)
{
for(int i = 1; i <= n; i++) cout << -1 << ' ';
return;
}
for(int i = 1; i <= n; i++) cout << --ans[i] << ' ';
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
solve();
return 0;
}
