#include <cstdlib>

#include <cstdio>

#include <cmath>

#include <cstring>

#include <algorithm>

#include <fstream>

#include <iostream>

#define rep(i, l, r) for(int i=l; i<=r; i++)

#define down(i, l, r) for(int i=l; i>=r; i--)

#define N 69

#define M 100009

using namespace std;

int read()

{

	int x=0, f=1; char ch=getchar();

	while (ch<'0' || ch>'9') { if (ch=='-') f=-1; ch=getchar(); }

	while (ch>='0' && ch<='9') { x=x*10+ch-'0'; ch=getchar(); }

	return x*f;

}

int n, l[N], r[N], k[M], b[M], ans, ansk[N], s;

bool Find(int x)

{

	rep(i, l[x], r[x]) if (b[i]!=s)

	{

		b[i]=s; if (!k[i] || Find(k[i])) { k[i]=x; return true; }

	}

	return false;

}

int main()

{

	int t=read(); while (t--)

	{

		n=read();

		rep(i, 1, n) l[i]=read(), r[i]=read();

		rep(i, 1, M-1) k[i]=b[i]=0;

		rep(i, 1, n) ansk[i]=0; ans=0;

		down(i, n, 1) if (Find(s=i)) ans++, ansk[i]=1;

		printf("%d\n", ans);

		rep(i, 1, n) if (ansk[i]) { if (--ans) printf("%d ", i); else printf("%d\n", i); }

	}

	return 0;

}