using System;
using System.Collections.Generic;
using System.Collections;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.IO;
using System.Reflection;
using static System.Math;
using System.Numerics;
using System.Threading;
using System.Runtime.CompilerServices;
using System.Diagnostics;
using nint=System.Int32;
static class Program{
	const int mod=(int)1e9+7;
	static void Main(){
		Sc sc=new Sc();
		var (n,m)=sc.Tp2<int>();
		St st=new St(n,1,true);
		var h=new int[m][];
		for(int i = 0;i<m;i++) {
			h[i]=sc.Ia;
			h[i][0]--;
			h[i][1]--;
			st.Add(h[i][0],h[i][1],h[i][2]);
		}
		var ans=new int[n];
		for(int i = 0;i<n;i++) {ans[i]=(int)st.Get(i);}
		Spt spt=new Spt(ans,false);
		for(int i = 0;i<m;i++) {
			if(spt.Get(h[i][0],h[i][1])!=h[i][2]){
				Console.WriteLine(-1);
				return;
			}
		}
		Console.WriteLine("{0}",string.Join(" ",ans));
	}
}
public class Spt{
	private readonly nint[][] d;
	private readonly int[] l;
	private Func<nint,nint,nint> Fu;
	public Spt(nint[] a,bool bo){
		int n=a.Length,m=(int)Log(n,2)+1;
		d=new nint[m][];
		d[0]=new nint[n];
		l=new int[n+1];
		if(bo){Fu=(y,x)=>Max(y,x);}
		else{Fu=(y,x)=>Min(y,x);}
		for(int i=0;i<n;i++){
			d[0][i]=a[i];
			l[i+1]=l[i>>1]+1;
		}
		for(int i=1,k=1;i<m;i++,k<<=1){
			int p=n+1-(k<<1);
			d[i]=new nint[p];
			for(int j=0;j<p;j++){d[i][j]=Fu(d[i-1][j],d[i-1][j+k]);}
		}
	}
	public nint Get(int a,int b){
		if(a>b){(a,b)=(b,a);}
		int p=l[b-a];
		return Fu(d[p][a],d[p][b+1-(1<<p)]);
	}
}
public class St{
	private long[] dat;
	private int m=1,cnt=0;
	private long d;
	private Func<long,long,long> Fm;
	public St(int n,long d,bool bo){
		if(bo){Fm=Fmax;}
		else{Fm=Fmin;}
		this.d=d;
		while(m<n){m<<=1;}
		cnt=m+n-1;
		dat=new long[cnt];
		for(int i = 0;i<cnt;i++) {dat[i]=d;}
	}
	private long Fmax(long a,long b){return Max(a,b);}
	private long Fmin(long a,long b){return Min(a,b);}
	public long Get(int q){
		long p=d;
		q+=m-1;
		while(q>=0){p=Fm(dat[q],p);q=(q-1)>>1;}
		return p;
	}
	public void Add(int a,int b,long d){Hn(a,b,0,0,m-1,d);}
	private void Hn(int a,int b,int k,int l,int r,long d){
		if(a<=l&&r<=b){dat[k]=Fm(dat[k],d);}
		else if(l<=b&&a<=r){
			Hn(a,b,k*2+1,l,(l+r)>>1,d);
			Hn(a,b,k*2+2,(l+r+1)>>1,r,d);
		}
	}
}
public class Sc{
	public int I{get{return int.Parse(Console.ReadLine());}}
	public long L{get{return long.Parse(Console.ReadLine());}}
	public double D{get{return double.Parse(Console.ReadLine());}}
	public string S{get{return Console.ReadLine();}}
	public int[] Ia{get{return Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}}
	public long[] La{get{return Array.ConvertAll(Console.ReadLine().Split(),long.Parse);}}
	public double[] Da{get{return Array.ConvertAll(Console.ReadLine().Split(),double.Parse);}}
	public string[] Sa{get{return Console.ReadLine().Split();}}
	public object[] Oa{get{return Console.ReadLine().Split();}}
	public int[] Ia2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),int.Parse);}}
	public int[] Ia3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),int.Parse);}
	public int[] Ia3(int a){return Array.ConvertAll((Console.ReadLine()+" "+a.ToString()).Split(),int.Parse);}
	public long[] La2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),long.Parse);}}
	public long[] La3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),long.Parse);}
	public long[] La3(int a){return Array.ConvertAll((Console.ReadLine()+" "+a.ToString()).Split(),long.Parse);}
	public double[] Da2{get{return Array.ConvertAll(("0 "+Console.ReadLine()+" 0").Split(),double.Parse);}}
	public double[] Da3(string a,string b){return Array.ConvertAll((a+Console.ReadLine()+b).Split(),double.Parse);}
	public T[] Arr<T>(int n,Func<T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f();}return a;}
	public T[] Arr<T>(int n,Func<int,T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i);}return a;}
	public T[] Arr<T>(int n,Func<string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(Console.ReadLine().Split());}return a;}
	public T[] Arr<T>(int n,Func<int,string[],T> f){var a=new T[n];for(int i=0;i<n;i++){a[i]=f(i,Console.ReadLine().Split());}return a;}
	public (T,T) Tp2<T>(){var s=Console.ReadLine().Split();return (Ct<T>(s[0]),Ct<T>(s[1]));}
	public (T,T,T) Tp3<T>(){var s=Console.ReadLine().Split();return (Ct<T>(s[0]),Ct<T>(s[1]),Ct<T>(s[2]));}
	public (T,T,T,T) Tp4<T>(){var s=Console.ReadLine().Split();return (Ct<T>(s[0]),Ct<T>(s[1]),Ct<T>(s[2]),Ct<T>(s[3]));}
	public (T1,T2) Tp2<T1,T2>(){var s=Console.ReadLine().Split();return (Ct<T1>(s[0]),Ct<T2>(s[1]));}
	public (T1,T1,T2) Tp3<T1,T2>(){var s=Console.ReadLine().Split();return (Ct<T1>(s[0]),Ct<T1>(s[1]),Ct<T2>(s[2]));}
	private T Ct<T>(string s){return (T)Convert.ChangeType(s,typeof(T));}
}