#include <bits/stdc++.h>
inline int read() {
  int s = 0;
  char c;
  while ((c = getchar()) < '0' || c > '9')
    ;
  do {
    s = s * 10 + c - '0';
  } while ((c = getchar()) >= '0' && c <= '9');
  return s;
}
int n, l, r, ql, qr;
long long ans;
int main() {
  for (n = read(), l = r = read(); n--;) {
    ql = read(), qr = read();
    if (ql <= l && r <= qr) continue;
    if (qr < l)
      ans += l - qr, r = l, l = qr;
    else if (r < ql)
      ans += ql - r, l = r, r = ql;
    else
      l = ql > l ? ql : l, r = qr < r ? qr : r;
  }
  printf("%I64d\n", ans);
  return 0;
}
