#include <algorithm> #include <iostream> #include <vector> using namespace std; using i64 = long long; constexpr int V = 1e9; int n; vector<int> a; bool check(int ans) { int l = 1, r = 1; i64 len = 2 * ans + 1; for (; r <= n; ++r) { if (a[l] + len <= a[r]) break; } l = r; for (; r <= n; ++r) { if (a[l] + len <= a[r]) break; } l = r; for (; r <= n; ++r) { if (a[l] + len <= a[r]) break; } return r > n; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr); cin >> n; a.resize(n + 1); for (int i = 1; i <= n; ++i) cin >> a[i]; sort(a.begin(), a.end()); int l = 0, r = V; while (l < r) { int mid = (l + r) >> 1; if (check(mid)) r = mid; else l = mid + 1; } cout << l << endl; return 0; }