#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
using namespace std;
#define fi first
#define sc second
#define mkp make_pair
#define pii pair<int,int>
typedef long long ll;
const int N=1e5+5,oo=1e9+5;
inline int read() {
    int x=0,flag=0;char ch=getchar();
    while(ch<'0'||ch>'9') {flag|=(ch=='-');ch=getchar();}
    while('0'<=ch&&ch<='9') {x=(x<<3)+(x<<1)+ch-'0';ch=getchar();}
    return flag?-x:x;
}
inline int mx(int x,int y) {return x>y?x:y;}
inline int mn(int x,int y) {return x<y?x:y;}
inline void swp(int &x,int &y) {x^=y^=x^=y;}
inline int as(int x) {return x>0?x:-x;}

int n,b[N<<1],val[N<<1],Val[N<<1],lim[N<<1],vc[N],Vc[N],ans;
int f[N<<1][20],to[N<<1];
struct Node {
    int l,r;
    bool operator <(const Node &w) {
        return r<w.r;
    }
}a[N];
int main() {
    int TT=read();
    while(TT--) {
        n=read();vc[0]=Vc[0]=b[0]=0;
        for(int i=1;i<=n;++i) a[i].l=read(),a[i].r=read(),b[++b[0]]=a[i].l,b[++b[0]]=a[i].r;
        sort(b+1,b+b[0]+1);b[0]=unique(b+1,b+b[0]+1)-b-1;
        for(int i=1;i<=n;++i) a[i].l=lower_bound(b+1,b+b[0]+1,a[i].l)-b,a[i].r=lower_bound(b+1,b+b[0]+1,a[i].r)-b;
        sort(a+1,a+n+1);
        int pre=-oo;
        for(int i=1;i<=n;++i) if(pre<a[i].l) {
            pre=a[i].r;
            vc[++vc[0]]=pre;
        }
        ans=0;
        for(int i=1,p1,p2;i<=n;++i) {
            p1=lower_bound(vc+1,vc+vc[0]+1,a[i].l)-vc;
            p2=upper_bound(vc+1,vc+vc[0]+1,a[i].r)-vc-1;
            ans=mx(ans,p2-p1+1);
        }
        for(int i=1;i<=b[0]+1;++i) val[i]=Val[i]=b[0]+1,lim[i]=0;
        for(int i=1;i<=n;++i) val[a[i].l]=mn(val[a[i].l],a[i].r),Val[a[i].l]=a[i].l,lim[a[i].l]=mx(lim[a[i].l],a[i].r);
        for(int i=b[0]-1;i>=1;--i) val[i]=mn(val[i],val[i+1]),Val[i]=mn(Val[i],Val[i+1]);
        for(int i=2;i<=b[0];++i) lim[i]=mx(lim[i-1],lim[i]);
        for(int i=1;i<=b[0]+1;++i) f[i][0]=val[i+1];
        f[b[0]+1][0]=b[0]+1;
        for(int j=1;j<=17;++j)
            for(int i=1;i<=b[0]+1;++i)
                f[i][j]=f[f[i][j-1]][j-1];
        for(int i=1;i<=b[0];++i) {
            int now=i;
            for(int j=17;j>=0;--j)
                if(((ans-1)>>j)&1) now=f[now][j];
            to[i]=now;
        }
        int pos=1;
        while(pos<=b[0]) {
            if(lim[pos]<to[pos]&&(Vc[0]<ans-1||lim[Vc[Vc[0]-(ans-1)+1]]<pos)) {
                Vc[++Vc[0]]=pos;
                pos=Val[pos+1];
            } else ++pos;
        }
        bool fl=1;
        for(int i=1,p1,p2;i<=n;++i) {
            p1=lower_bound(Vc+1,Vc+Vc[0]+1,a[i].l)-Vc;
            p2=upper_bound(Vc+1,Vc+Vc[0]+1,a[i].r)-Vc-1;
            if(p2-p1+1==0) fl=0;
        }
        if(fl) {
            printf("%d %d ",ans-1,Vc[0]);
            for(int i=1;i<=Vc[0];++i) printf("%d ",b[Vc[i]]);
            printf("\n");
        } else {
            printf("%d %d ",ans,vc[0]);
            for(int i=1;i<=vc[0];++i) printf("%d ",b[vc[i]]);
            printf("\n");
        }
    }
    return 0;
}