#include <iostream> #include <cstdio> #include <cstring> #include <cctype> #define maxn 500010 using namespace std; int d,n,m; int a[maxn]; int l,r,mid,ans; inline int read(){ int num = 0; char c; bool flag = false; while ((c = getchar()) == ' ' || c == '\n' || c == '\r'); if (c == '-') flag = true; else num = c - '0'; while (isdigit(c = getchar())) num = num * 10 + c - '0'; return (flag ? -1 : 1) * num; } bool judge(int x){ int tot = 0; int i = 0; int now = 0; while (i < n+1){ i++; if (a[i] - a[now] < x) tot++; else now = i; } if (tot > m) return false; else return true; } int main(){ d = read(); n = read(); m = read(); for (int i=1;i<=n;i++) a[i] = read(); a[n+1] = d; l = 1; r = d; while (l <= r){ / 2; if (judge(mid)){ ans = mid; l = mid + 1; } else r = mid - 1; } cout << ans << endl; return 0; }