#include <cstdio>

int main() {
	int n, k, a, b, min;
	int prevA, prevB, prevJA = 0, prevJB = 0;
	
	scanf("%d", &n);
	for(int i = 0; i < n; ++i) {
		scanf("%d", &k);
		scanf("%d%d", &a, &b);
		prevA = a;
		prevB = b;
		min = b - a;
		prevJB = prevJA = 0;
		
		for(int j = 1; j < k; ++j) {
			scanf("%d%d", &a, &b);
				if (b - a < min) min = b - a;
				if (b - prevA < 0 && j - prevJA - 1 < min) min = j - prevJA - 1;
				else if (b - prevA + j - prevJA < min) min = b - prevA + j - prevJA;
				if (prevB - a < 0 && j - prevJB - 1 < min) min = j - prevJB - 1;
				else if (prevB - a + j - prevJB < min) min = prevB - a + j - prevJB;
				if (b + prevJB < prevB + j) {
					prevB = b;
					prevJB = j;
				}
				if (a + j  > prevA + prevJA) {
					prevA = a;
					prevJA = j;
				}
		}
		printf("K prechodu reky je potreba %d pontonu.\n", min);		
		
	}
	return 0;	
}