#include <bits/stdc++.h>
using namespace std;
double maxx,sum;
int n,m,jj;
int main(){
	cin>>n>>m;
	for (int i=1;i<=n;i++){
		sum=0;
		for (int j=1;j<=m;j++){
			cin>>jj;
			sum+=jj;
		}
		sum/=m;
		if (sum>=maxx){
			maxx=sum;
		}
	}
	printf ("%.2f",maxx);
	return 0;
}