// #pragma comment(linker, "/STACK:102400000,102400000")
#pragma GCC optimize("O3")
#pragma GCC optimize("O2")
// #pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
// #pragma GCC optimize("trapv")
#include<bits/stdc++.h>
// #include <bits/extc++.h>
#define int long long
#define double long double
// #define i128 long long
// #define double long double
using namespace std;
 
#define rep(i,n) for (int i=0;i<(int)(n);++i)
#define rep1(i,n) for (int i=1;i<=(int)(n);++i)
#define range(x) begin(x), end(x)
#define sz(x) (int)(x).size()
#define pb push_back
#define F first
#define S second
 
typedef long long ll;
typedef unsigned long long ull;
// typedef long double ld;
typedef pair<int, int> pii;
typedef vector<int> vi;


int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};
// const int mod[]={998244353,(int)1e9+7};
const int mod=998244353;
const int base[]={12321,32123};
const double EPS=8e-6;
// const double pi=acos(-1);
const int INF=1e12;
const int N=1500007;
mt19937 rng(1235);
const int B=500;

int l[N], r[N],p[N];
int ans[N];
vi lst[N];
signed main(){
  ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  cout.precision(15);
  int _;
  cin>>_;
  while (_--){
    int n,m;
    cin>>n>>m;
    rep(i,2*m) cin>>l[i]>>r[i], l[i]--;
    int sum=0;
    rep(i,2*m) {
        if (r[i]==l[i]+1) sum++;
    }
    if (sum>m){
        cout<<"-1\n";
        continue;
    }
    rep(i,2*m) p[i]=i;
    sort(p,p+2*m,[&](int u,int v){return (r[u]-l[u]<r[v]-l[v])||(r[u]-l[u]==r[v]-l[v]&&l[u]<l[v]);});
    rep(i,n+2) lst[i].clear();
    rep(i,m) lst[l[p[i]]].pb(1);
    rep(i,m) lst[r[p[i]]].pb(~l[p[i]]);
    map<int,int> nw;
    set<int> rem;
    for (int i=0;i<n+3;++i) rem.insert(i);
    int L=0;
    for (int i=0;i<n;++i){
        for (auto c:lst[i]){
            if (c>0) nw[i]++;
            else {
                nw[~c]--;
                if (!nw[~c]) nw.erase(~c);
            }
        }
        int ret;
        if (!sz(nw)) ret=i;
        else ret=nw.begin()->F;
        for (;L<ret;L++) rem.insert(ans[L]);
        ans[i]=*rem.begin();
        rem.erase(ans[i]);
    }
    rep(i,n) cout<<ans[i]+2<<" ";
    cout<<"\n";
  }
  return 0;
}
/*
3
2 1
1 1
2 2
6 2
1 3
4 6
2 4
3 5
4 3
1 2
1 1
2 2
2 3
3 3
3 4
*/