#include <bits/stdc++.h>
using namespace std;
const int NMAX=2e5;
int n, q, l[NMAX+5], r[NMAX+5], l2[NMAX+5], r2[NMAX+5], ans[NMAX+5];
void blud ()
{
for (int i=0;i<n;i++)
{
cout << "-1 ";
}
exit (0);
}
int main ()
{
ios_base :: sync_with_stdio (0);
cin.tie (nullptr);
cin >> n >> q;
for (int i=0;i<n;i++)
r2[i]=l[i]=-1, l2[i]=r[i]=1e9;
while (q--)
{
int x, y, val;
cin >> x >> y >> val;
l[val]=max (l[val], x);
r[val]=min (r[val], y);
l2[val]=min (l2[val], x);
r2[val]=max (r2[val], y);
}
set <int> pos, cows;
for (int i=0;i<n;i++)
pos.insert (i), cows.insert (i);
for (int i=n-1;i>=0;i--)
{
if (l[i]==-1)
continue;
auto itr=pos.lower_bound (l[i]);
if (itr==pos.end() || (*itr)>r[i])
blud ();
ans[*itr]=i;
pos.erase (*itr);
cows.erase (i);
while (pos.size())
{
auto itr=pos.lower_bound (l2[i]);
if (itr==pos.end() || (*itr)>r2[i])
break;
int x=*cows.rbegin();
if (x<i)
blud ();
ans[*itr]=x;
pos.erase (itr);
cows.erase (x);
}
}
while (pos.size())
{
ans[*pos.begin()]=*cows.begin();
pos.erase (pos.begin());
cows.erase (cows.begin());
}
for (int i=0;i<n;i++)
cout << ans[i] << " ";
return 0;
}
