func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, x;     cin >> n >> x;     int pos = 1;     long long ans = 0;     for (int i = 0; i < n; i++) {       int l, r;       cin >> l >> r;       ans += 1LL * (l - pos) % x + (r - l + 1);       pos = r + 1;     }     cout << ans << endl;     return 0;   }   