#include <bits/stdc++.h> #define int long long using namespace std; double a[105],s[105]; signed main(){ int n,m; cin >> n >> m; for(int i=1;i<=n;i++){ cin >> a[i]; s[i]=s[i-1]+a[i]; } double maxn=0; for(int i=1;i<=n-m+1;i++){ maxn=max(maxn,(s[i+m-1]-s[i-1])/m); } cout << fixed << setprecision(2) << maxn; return 0; }