#include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(NULL);     ;     long long t;     cin >> t;     while (t--) {       long long n, x, m;       cin >> n >> x >> m;       long long c, d;       long long l = x, r = x;       while (m--) {         cin >> c >> d;         if (c <= l && d >= r) {           l = c;           r = d;         } else if (c <= l && d <= r && d >= l)           l = c;         else if (l <= c && c <= r && d >= r)           r = d;       }       cout << (r - l + 1) <<   n ;     }     return 0;   }   