#include <bits/stdc++.h>
//#define no_sol { cout << "-1\n"; exit(0); }
using namespace std;
///11:12
const int Nmax = 1e5 + 5;
set<int> S;
int last, n, m;
vector<pair<int,int>> v[Nmax];
bool used[Nmax];
int ans[Nmax];
void no_sol()
{
int i;
for(i=0; i<n; ++i) cout << "-1 ";
exit(0);
}
void add(int val, int start, int finish, int L, int R)
{
set<int> :: iterator it = S.lower_bound(start), it2 = it;
bool added = 0;
while(it != S.end() && *it <= finish)
{
if(*it >= L && *it <= R && !added)
{
assert(used[val] == 0);
ans[*it] = val;
used[val] = 1;
added = 1;
}
else
{
while(last>=0 && used[last]) --last;
if(last <= val) no_sol();
used[last] = 1;
ans[*it] = last;
}
++it;
}
if(!added) no_sol();
S.erase(it2, it);
}
int main()
{
// freopen("input", "r", stdin);
cin.sync_with_stdio(false); cin.tie(0);
cin >> n >> m;
int i;
for(i=1; i<=m; ++i)
{
int x, y, val;
cin >> x >> y >> val;
v[val].push_back({x, y});
}
for(i=0; i<n; ++i) S.insert(i);
last = n-1;
for(i=n-1; i>=0; --i)
if(v[i].size())
{
int lmin, rmax, lmax, rmin;
lmin = rmin = n-1;
lmax = rmax = 0;
for(auto it : v[i])
{
int x, y;
tie(x, y) = it;
lmin = min(lmin, x);
lmax = max(lmax, x);
rmin = min(rmin, y);
rmax = max(rmax, y);
}
if(lmax > rmin) no_sol();
add(i, lmin, rmax, lmax, rmin);
}
for(auto it : S)
{
while(last>=0 && used[last]) --last;
if(last < 0) no_sol();
ans[it] = last;
used[last] = 1;
}
for(i=0; i<n; ++i) cout << ans[i] << ' ';
return 0;
}
