#include <iostream>#include <cstdio>#include <cstdlib>#include <cstring>#include <algorithm>using namespace std;#define maxn 50005int p, n, m, ans;int rock[maxn];bool ok(int l){ int d =0; int j =0; int t = n -1; while (t >=0&& rock[n -1] - rock[t] < l) t--; if (t <0) return false; d = n - t -1-1; for (int i =1; i <= t; i++) if (rock[i] - rock[j] < l) d++; else j = i; if (d <= m) return true; return false;}void binarysearch(){ int l =1; int r = p; while (l < r) { int mid = (l + r) /2; mid += (l + r) &1; if (ok(mid)) l = mid; else r = mid -1; } ans = l;}int main(){ scanf("%d%d%d", &p, &n, &m); rock[0] =0; rock[1] = p; for (int i =2; i <= n +1; i++) scanf("%d", &rock[i]); n +=2; sort(rock, rock + n); binarysearch(); printf("%dn", ans); return 0;}
