#include<iostream>

#include<vector>
#include<algorithm>
#include<stack>
#include<map>
#include<queue>
#include<list>
#include<string>

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

using namespace std;

#define FOR(i,a,b) for(int i=a; i<=b; i++)
#define PB push_back
#define fi first
#define se second
#define make_pair
#define PII pair<int, int>

#define SIZE(s) (int)(s).size()

#define INF 987654321
#define ll long long

//----------

int N, K;
ll a, b;

int main() {
	scanf("%d", &N);
	while (N--) {
		scanf("%d", &K);
		
		ll best = INF;
		ll bl_pos = -1LL;
		ll bl_val = -1LL;

		FOR(i, 0, K-1) {
			scanf("%lld %lld", &a, &b);
			if (bl_pos == -1LL) {
				bl_pos = (ll) i;
				bl_val = a;
			} else {
				if (i+a >= (bl_pos + bl_val)) {
					bl_pos = (ll) i;
					bl_val = a;
				}
			}

			ll v = ( (ll)i-bl_pos) + (b-bl_val);
			best = min(best, v);
		}
		printf("K prechodu reky je treba %lld pontonu.\n", best);
	}
	return 0;
}