#include <cstdio>
#include <cstdlib>
#include <string>
#include <iostream>

#define REP(i, cnt) for (int i = 0; i < (cnt); i++)

#define N 19

using namespace std;
typedef long long int64;

int ldist[1000004];
int rdist[1000004];

int main() {
	
	int inputcount;
	
	scanf("%d", &inputcount);
	REP(inp, inputcount) {
	
		int rows;
		scanf("%d", &rows);
		
		REP(i, 1000004) {
			ldist[i] = -1;
			rdist[i] = -1;
		}
		
		int best = 999999999;
		int prevb = 999999999;
		REP(row, rows) {
			int a, b;
			scanf("%d%d", &a, &b);
			a++, b++;
			
			for (int x = 0; x < a; x++)
				ldist[x] = 0;
			ldist[a] = 1;
			for (int x = a+1; x <= b; x++) {
				if (x > 0 && ldist[x-1] >= 0 && (ldist[x-1] < ldist[x] || ldist[x] < 0))
					ldist[x] = ldist[x-1];
				if (ldist[x] >= 0)
					ldist[x]++;
			}
			if (ldist[b]-1 < best)
				best = ldist[b]-1;
				
			rdist[b] = 0;
			for (int x = b-1; x >= a-1; x--) {
				if (x >= prevb)
					rdist[x] = 1;
				else if (rdist[x+1] >= 0 && (rdist[x+1] < rdist[x] || rdist[x] < 0))
					rdist[x] = rdist[x+1];
				if (rdist[x] >= 0)
					rdist[x]++;
			}
			if (rdist[a-1]-1 < best)
				best = rdist[a-1]-1;
			
			prevb = b;
		}
		printf("K prechodu reky je treba %d pontonu.\n", best);
	
	
	}
	
	
	return 0;
}