#include <iostream>
#include <cstdio>
#include <vector>
#include <iterator>
#include <algorithm>
#include <utility>
#include <limits>

static const int r_size = 1000002;


int main(){
     
    int N;
    std::scanf("%d", &N);
    
    for (int n = 0; n < N; ++n){
        std::vector<int> river_l(r_size, std::numeric_limits<int>::max());
        std::vector<int> river_r(r_size, std::numeric_limits<int>::max());
        int height;
        int min_r = std::numeric_limits<int>::max();
        int min_l = std::numeric_limits<int>::max();
        int optimum = std::numeric_limits<int>::max();
        std::scanf("%d", &height);

        for (int h = 0; h < height; ++h){
            int left, right, i;
            std::scanf("%d %d", &left, &right);
            if (h == 0) { min_r = right; min_l = left; } // Ooops
            
            
            for (i=left; i<min_l; ++i) {
                river_l[i] = 1;
            }
            
            river_l[left] = 1;
            
            for (i=std::max(left+1, min_l); i<right; ++i) {
                river_l[i] = std::min(river_l[i-1], river_l[i]) + 1;
                
                if (i == min_r) {
                    if (river_l[i] < optimum) {
                        optimum = river_l[i];
                    }
                }
            }
            
//            printf("Height %d: left %d, right %d, river %d\n", h, left, right, river_l[right-1]);
            if (river_l[right-1] < optimum) {
                optimum = river_l[right-1];
            }
            
            for (; i<min_r; ++i) {
                if (river_l[i] < optimum) {
                    optimum = river_l[i];
                }
            }
            
            // ---
            
            for (i=right-1; i>=min_r; --i) {
                river_r[i] = 1;
            }
            
            river_r[right-1] = 1;
            
            for (i=std::min(right-2, min_r-1); i>=left; --i) {
                river_r[i] = std::min(river_r[i+1], river_r[i]) + 1;
            
                if (i == min_l-1) {
                    if (river_r[i] < optimum) {
                        optimum = river_r[i];
                    }
                }    
            }
            
            if (river_r[left] < optimum) {
                optimum = river_r[left];
            }
            
            for (; i>=min_l; --i) {
                if (river_r[i] < optimum) {
                    optimum = river_r[i];
                }
            }
            
            min_l = left;
            min_r = right;
        }
        
        printf("K prechodu reky je treba %d pontonu.\n", optimum);
        
    }

    return 0;
}