#include<bits/stdc++.h>
//#pragma GCC optimize("O3")
//#pragma GCC target ("sse4")
using namespace std;
#define pb push_back
#define all(x) (x).begin(),(x).end()
#define MEM(x,a) memset((x),a,sizeof((x)))
#define F first
#define S second
#define L (idx*2)
#define R (L+1)
#define imx INT_MAX
const long long MOD = (long long)(1e9+7);
const long long MMX = (long long)(1e18);
typedef long long LL;
typedef pair<int,int> pii;
int n,k,N,cn[100005],seq[800010],pr,mx,ss;
set<int>s;
vector<int>puu[100005];
map<int,int>mp;
struct node
{
int l,r;
}ev[100005];
vector<int>sor;
priority_queue<pii>pq;
void seq_up(int st,int ed,int idx,int pos,int val)
{
int mid=(st+ed)/2;
if(pos<st||pos>ed)return;
if(st==ed)
{
seq[idx]=max(seq[idx],val);
return;
}
seq_up(st,mid,L,pos,val);
seq_up(mid+1,ed,R,pos,val);
seq[idx]=max(seq[L],seq[R]);
return;
}
int seq_mx(int st,int ed,int idx,int ll,int rr)
{
int mid=(st+ed)/2;
if(rr<st||ll>ed)return 0;
if(ll<=st&&rr>=ed)return seq[idx];
return max(seq_mx(st,mid,L,ll,rr),seq_mx(mid+1,ed,R,ll,rr));
}
int main()
{
scanf("%d %d",&n,&k);
for(int i=1;i<=n;i++)
{
scanf("%d %d",&ev[i].l,&ev[i].r);
if(mp[ev[i].l]==0)
{
sor.pb(ev[i].l);
mp[ev[i].l]=1;
}
if(mp[ev[i].r]==0)
{
sor.pb(ev[i].r);
mp[ev[i].r]=1;
}
}
sort(all(sor));
for(int i=0;i<sor.size();i++)
{
mp[sor[i]]=i+1;
}
N=sor.size();
sor.clear();
for(int i=1;i<=n;i++)
{
ev[i].l=mp[ev[i].l];
ev[i].r=mp[ev[i].r];
pq.push({ev[i].l,i});
}
while(!pq.empty())
{
pr=pq.top().S;
pq.pop();
mx=seq_mx(1,N,1,ev[pr].r,N);
seq_up(1,N,1,ev[pr].l,mx+1);
cn[pr]=mx+1;
}
ss=imx;
for(int i=1;i<=n;i++)
{
if(cn[i]>=k)
{
ss=min(i,ss);
}
puu[cn[i]].pb(i);
}
if(ss==imx)
{
printf("-1");
}
else
{
sor.pb(ss);
for(int i=n;i>=k;i--)
{
for(int j=0;j<puu[i].size();j++)
{
s.insert(puu[i][j]);
pq.push({-ev[puu[i][j]].l,puu[i][j]});
}
}
for(int i=k-1;i>0;i--)
{
for(int j=0;j<puu[i].size();j++)
{
s.insert(puu[i][j]);
pq.push({-ev[puu[i][j]].l,puu[i][j]});
}
while(-pq.top().F<ev[ss].r)
{
s.erase(pq.top().S);
pq.pop();
}
ss=*(s.begin());
sor.pb(ss);
}
sort(all(sor));
for(int i=0;i<sor.size();i++)
{
printf("%d\n",sor[i]);
}
}
}
