#include<bits/stdc++.h>
using namespace std;
int main(){
	int i,j,s,n,a,b,h,c[100][3]={0};
	float max_=0;
	cin>>n;
	for(i=0;i<n;i++){
		for(j=0;j<3;j++){
			cin>>c[i][j];	
		}
	}
	for(i=0;i<n;i++){
		a=c[i][0];
		b=c[i][1];
		h=c[i][2];	
		s=(a+b)*h/2.0;
		if(max_<s){
			max_=(a+b)*h/2.0;
		}
	}printf("%.1f",max_);
}

/**************************************************************
	Problem: 1330
	User: chenjiahui
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2076 kb
****************************************************************/