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