POST - VNUOI 2021

//Make CSP great again
//You're as beautiful as the day I lost you
//New year, best wishes
#include <bits/stdc++.h>
#define TASK "TESTCODE"
#define Log2(x) 31 - __builtin_clz(x)
using namespace std;
const int N = 1e5;
int n, a[N + 3];
void read()
{
    cin >> n >> a[1] >> a[2];
    for (int i = 3; i <= n + 2; ++ i)
    {
        cin >> a[i];
    }
}
bool check(int k)
{
    set<int> dp = {a[1]};
    set<int> :: iterator it;
    for (int i = 2; i < n + 2; ++ i)
    {
        if (dp.empty())
        {
            return false;
        }
        if (abs(a[i] - a[i + 1]) <= k)
        {
            dp.insert(a[i]);
        }
        while(!dp.empty() && a[i + 1] - *dp.begin() > k)
        {
            it = dp.begin();
            dp.erase(it);
        }
        while(!dp.empty() && *dp.rbegin() - a[i + 1] > k)
        {
            it = dp.end();
            --it;
            dp.erase(it);
        }
    }
    return !dp.empty();
}
void solve()
{
    int low = abs(a[2] - a[1]), high = 1e9;
    while(low <= high)
    {
        int mid = (low + high)/2;
        if (check(mid))
        {
            high = mid - 1;
        }
        else
        {
            low = mid + 1;
        }
    }
    cout << low;
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    if (fopen(TASK".INP", "r"))
    {
        freopen(TASK".INP", "r", stdin);
        //freopen(TASK".out", "w", stdout);
    }
    int t = 1;
    bool typetest = false;
    if (typetest)
    {
        cin >> t;
    }
    for (int __ = 1; __ <= t; ++ __)
    {
        //cout << "Case " << __ << ": ";
        read();
        solve();
    }
}