#include <bits/stdc++.h>
using namespace std;
int main(){
	int n,i,j;
	cin>>n;
	float ss,a=0;
	float s[100][3]={0};
	for(i=0;i<n;i++){
		for(j=0;j<3;j++){
			cin>>s[i][j];		
		}
		ss=s[i][0]+s[i][1];
		ss=ss*s[i][2]*1.0/2;
		if(a<ss)
			a=ss;
	}
	
	printf("%.1f",a);	
	return 0;
	}
/**************************************************************
	Problem: 1330
	User: fzy001
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2072 kb
****************************************************************/