#include <iostream> #include <bits/stdc++.h> #define ll long long using namespace std; const ll maxn = 2*1e5+5, INF = 4e18+9; void solve(){ int n, T; cin >> n >> T; vector<int> a(n+1); for(int i = 1; i <= n; i++){ cin >> a[i]; } for(int i = 1; i <= n; i++){ a[i] %= T; } sort(a.begin()+1, a.end()); ll ans = (a[n] - a[1] + 1)/2; for(int i = 2; i <= n; i++){ ll len = T + a[i-1] - a[i]; len++; ll mx = len/2; ans = min(ans, mx); } cout << ans; } int main(){ ios_base::sync_with_stdio(false); cin.tie(NULL); solve(); }