#include <bits/stdc++.h>
using namespace std;
int n, s1, s2;
int a[100005];
bool check(int x) {
  int l = -1e9, r = 1e9;
  for (int i = n; i >= 1; i--) {
    if (l <= a[i] && a[i] <= r) {
      l = a[i] - x;
      r = a[i] + x;
    } else {
      l = max(l, a[i] - x);
      r = min(r, a[i] + x);
    }
  }
  return (l <= s1 && s1 <= r) || (l <= s2 && s2 <= r);
}
int main() {
  scanf("%d%d%d", &n, &s1, &s2);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &a[i]);
  }
  int l = abs(s1 - s2), r = 1e9, ans = 1e9;
  while (l <= r) {
    int mid = (l + r) / 2;
    if (check(mid)) {
      r = mid - 1;
      ans = mid;
    } else {
      l = mid + 1;
    }
  }
  printf("%d", ans);
  return 0;
}
