#include <bits/stdc++.h>
using namespace std;

const int N = 1100;
const int inf = 1000000007;
int l[N], r[N], dp[N][6];

int calc_step(int x, int y){
    int t = abs(y - x);
    return (t + 1) >> 1;
}

int main(){
    //freopen("a.in", "r", stdin);
    //freopen("a.out", "w", stdout);
    int i, j, k, T, n, ne_real_l, ne_real_r, real_l, real_r;
    scanf("%d", &T);
    while (T--){
        scanf("%d", &n);
        for (i = 1; i <= n; i++){
            scanf("%d%d", &l[i], &r[i]);
        }
        int ans = inf;
        memset(dp, 0x7f, sizeof(dp));
        real_l = 1;
        real_r = 1000000;
        for (i = 1; i <= n; i++){
            real_l = max(real_l, l[i]);
            real_r = min(real_r, r[i]);
            if (real_l > real_r){
                break;
            }
            for (j = 1; j <= 4; j++){
                int pos;
                if (j <= 2){
                    pos = l[i] + j - 1;
                }
                else{
                    pos = r[i] - (4 - j);
                }
                if ((pos < l[i]) || (pos > r[i])){
                    continue;
                }
                if ((pos >= real_l) && (pos <= real_r)){
                    dp[i][j] = 0;
                }
            }    
        }
        if (i > n){
            printf("0\n");
            continue;
        }
        

        for (i = 1; i < n; i++){
            for (j = 1; j <= 4; j++){
                int pos;
                if (j <= 2){
                    pos = l[i] + j - 1;
                }
                else{
                    pos = r[i] - (4 - j);
                }
                if ((pos < l[i]) || (pos > r[i])){
                    continue;
                }
                int trans_to = i + 1;
                while ((trans_to <= n) && ((l[trans_to] <= pos) && (pos <= r[trans_to]))){
                    trans_to++;
                }
                if (trans_to > n){
                    ans = min(ans, dp[i][j]);
                    continue;
                }
                else{
                    for (k = 1; k <= 4; k++){
                        int ne_pos;
                        if (k <= 2){
                            ne_pos = l[trans_to] + k - 1;
                        }
                        else{
                            ne_pos = r[trans_to] - (4 - k);
                        }
                        if ((ne_pos < l[trans_to]) || (ne_pos > r[trans_to])){
                            continue;
                        }
                        dp[trans_to][k] = min(dp[trans_to][k], dp[i][j] + calc_step(pos, ne_pos));
                    }
                }
            }
        }
        for (j = 1; j <= 4; j++){
            ans = min(ans, dp[n][j]);
        }
        printf("%d\n", ans);
    }
    return 0;
}