#include <bits/stdc++.h>
using namespace std;
const int N = 100005;
int sz = 1;
int t[N << 2], clr[N << 2];
inline void pushclear(int k) {
  if (!clr[k]) return;
  t[k] = 0;
  if (k < sz) clr[k << 1] = clr[k << 1 | 1] = 1;
  clr[k] = 0;
}
inline void clear(int k, int l, int r, int a, int b) {
  pushclear(k);
  if (a > r || b < l) return;
  if (a >= l && b <= r) {
    clr[k] = 1;
    pushclear(k);
    return;
  }
  int mid = (a + b) >> 1;
  clear(k << 1, l, r, a, mid), clear(k << 1 | 1, l, r, mid + 1, b);
  t[k] = t[k << 1] + t[k << 1 | 1];
}
inline void add(int k, int pos, int a, int b, int x) {
  pushclear(k);
  if (a == b) {
    t[k] += x;
    return;
  }
  int mid = (a + b) >> 1;
  if (pos <= mid)
    add(k << 1, pos, a, mid, x);
  else
    add(k << 1 | 1, pos, mid + 1, b, x);
  t[k] = t[k << 1] + t[k << 1 | 1];
}
int n, init_x, init_y;
int a[N];
vector<int> vec;
inline int getpos(int x) {
  return lower_bound(vec.begin(), vec.end(), x) - vec.begin() + 1;
}
bool check(int mid) {
  for (int i = 1; i < (sz << 1); i++) t[i] = clr[i] = 0;
  add(1, getpos(init_x), 1, sz, 1);
  add(1, getpos(init_y), 1, sz, 1);
  for (int i = 1; i <= n; i++) {
    int l = lower_bound(vec.begin(), vec.end(), a[i] - mid) - vec.begin() + 1;
    int r = lower_bound(vec.begin(), vec.end(), a[i] + mid) - vec.begin() + 1;
    if (r > vec.size() || vec[r - 1] > a[i] + mid) r--;
    if (l - 1 >= 1) clear(1, 1, l - 1, 1, sz);
    if (r + 1 <= sz) clear(1, r + 1, sz, 1, sz);
    if (t[1] == 0) return false;
    add(1, getpos(a[i]), 1, sz, 1);
  }
  return true;
}
int main() {
  scanf("%d%d%d", &n, &init_x, &init_y);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &a[i]);
    vec.emplace_back(a[i]);
  }
  vec.emplace_back(init_x);
  vec.emplace_back(init_y);
  sort(vec.begin(), vec.end());
  vec.resize(unique(vec.begin(), vec.end()) - vec.begin());
  while (sz < vec.size()) sz <<= 1;
  int l = abs(init_x - init_y), r = 1000000000, mid, ans;
  while (l <= r) {
    mid = (l + r) >> 1;
    if (check(mid))
      r = mid - 1, ans = mid;
    else
      l = mid + 1;
  }
  printf("%d\n", ans);
  return 0;
}
