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

int main(void) {
	int testCases = 0, height = 0, x1 = 0, x2 = 0, resX1, resY1, resX2, resY2, distance;
	
	scanf("%d", &testCases);
	for(int i = 0; i < testCases; i++){
		scanf("%d", &height);

		scanf("%d %d", &x1, &x2);
		//++x2;
		resX1 = x1; resX2 = x2; resY1 = resY2 = 0;
		distance = x2 - x1;
		for(int y = 1; y < height; y++){			
			scanf("%d %d", &x1, &x2);
			//++x2;
			if(((resX2 - x1) + (y - resY2)) < distance ){
				resX1 = x1;
				resY1 = y;
				distance = (resX2 - x1) + (y - resY2);
			}
			if(((x2 - resX1) + (y - resY1)) < distance ){
				resX2 = x2;
				resY2 = y;
				distance = (x2 - resX1) + (y - resY1);
			}
			if((x2 - x1) < distance){
				resX1 = x1;
				resX2 = x2;
				resY1 = resY2 = y;
				distance = (x2 - x1);
			}

		}

//		printf("[%d, %d] - [%d, %d] %d", resX1, resY1, resX2, resY2, distance);
		printf("K prechodu reky je treba %d pontonu.\n", distance);
	
	}
	return 0;
}