#include <stdio.h>
#include <algorithm>
#include <map>

using namespace std;

int n;
int a[1200] , b[1200];
map < pair<int,int> , int > m , v;
int ans;
int near ( int p , int i ) {
    if ( p == a[i] || p == a[i]+1 || p == b[i] || p == b[i-1] ) return 1;
    return 0;
}
int xx ( int p , int i ) {
    if ( i == n + 1 ) return 0;
    if ( near ( p , i ) )
        if ( i != 1 ) if ( v[make_pair(p,i)] ) return m[make_pair(p,i)];
    int t;
    if ( a[i] <= p && p <= b[i] ) t = xx (p,i+1);
    else {
        if ( p < a[i] ) {
            if ( (a[i]-p) % 2 == 0 || a[i] == b[i] ) t = xx ( a[i] , i + 1 ) + (a[i]-p+1) / 2;
            else t = min ( xx(a[i],i+1) , xx(a[i]+1,i+1) ) + (a[i]+1-p)/2;
        }
        else {
            if ( (p-b[i])%2== 0 || a[i]==b[i] ) t = xx(b[i],i+1) + (p-b[i]+1)/2;
            else t = min ( xx(b[i],i+1) , xx(b[i]-1,i+1) ) + (p-b[i]+1) / 2;
        }
    }
    if ( i == 1 || !near ( p , i ) ) return t;
    v[make_pair(p,i)] = 1;
    m[make_pair(p,i)] = t;
    return t;
}
int main () {
    int t , i;
    scanf ( "%d" , &t );
    while ( t-- ) {
        scanf ( "%d" , &n );
        m.clear(); v.clear ();
        ans = 2147483647;
        for ( i = 1 ; i <= n ; i++ ) {
            scanf ( "%d%d" , &a[i]  , &b[i] );
        }
        for ( i = a[1] ; i <= b[1] ; i++ ) {
            ans = min ( ans , xx ( i , 1 ) );
        }
        printf ( "%d\n" , ans );
    }
    return 0;
}