#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct river {
	int left;
	int right;
};

int main(void)
{
	int n, i;
	scanf("%d\n", &n);
	
	for(i = 0; i < n; i++)
	{
		int d, j;
		
		scanf("%d\n", &d);
		
		struct river * rivers = malloc(d* sizeof(struct river));
		unsigned min = -1;
		
		for(j = 0; j < d; j++)
		{
			scanf("%d %d\n", &rivers[j].left, &rivers[j].right);
		}
		
		
		for(j=0; j < d; j++)
		{
			int k;
			for(k = 0; k < d; k++)
			{
				int sidedif = (rivers[k].right- rivers[j].left);
				
				//printf("left: %d right: %d sidedif: %d",  rivers[j].left, rivers[k].right, sidedif);
				
				unsigned new_min = -1;
				
				if ( sidedif < 0 )
					new_min = j > k ? j - k : k - j;
				else
					new_min = sidedif + (j > k ? j - k : k - j);
				
				//printf("\tnewmin %u\n",  new_min);
				
				min = new_min < min ? new_min : min;
			}
		}
		
		free(rivers);
		
		printf("K prechodu reky je treba %d pontonu.\n", min);
	}
	
	return 0;
}