#include <bits/stdc++.h>
#include <atcoder/all>
//eolibraries
#define lnf 3999999999999999999
#define inf 999999999+1
#define fi first
#define se second
#define pb push_back
#define all(c) (c).begin(),(c).end()
#define sz(c) (int)(c).size()
#define make_unique(a) sort(all(a)),a.erase(unique(all(a)),a.end());
#define rep(i,n) for(int i=0;i<n;i++)
#define drep(i,n) for(int i=n-1;i>=0;i--)
#define crep(i,x,n) for(int i=x;i<n;i++)
#define vec(...) vector<__VA_ARGS__>
#define _3E0svGb ios_base::sync_with_stdio(false),cin.tie(0),cout.tie(0)
//eodefine
using namespace std;
typedef long long ll;
typedef long double ld;
using pii=pair<int,int>;
using tpii=pair<pii,int>;
using vi=vec(int);
const int mxn=12000;

ll op(ll l,ll r){
	return min(l,r);
}

ll e(){
	return lnf;
}

int main(){
_3E0svGb;
	int n,m;
	cin>>n>>m;
	atcoder::segtree<ll,op,e> seg(n);
	rep(i,n) seg.set(i,lnf);
	vec(vec(pii)) qry(n);
	ll mx=0;
	rep(i,m){
		ll l,r,val;
		cin>>l>>r>>val;
		l--,r--;
		mx=max(mx,val);
		qry[r].pb({l,val});	
	}
	mx++;
	rep(i,n){
		sort(all(qry[i]));
		for(auto p : qry[i]){
			ll val=p.se;
			if(seg.prod(p.fi,i+1)<val){
				printf("-1\n");
				exit(0);
			}
			seg.set(p.fi,val);
		}
	}
	rep(i,n){
		for(auto p : qry[i]){
			ll val=p.se;
			if(seg.prod(p.fi,i+1)!=val){
				printf("-1\n");
				exit(0);
			}
		}
	}
	rep(i,n){
		cout<<(seg.prod(i,i+1)==lnf?mx:seg.prod(i,i+1));
		if(i<n-1) cout<<" ";
	}
	cout<<"\n";
//	
	return 0;
}