#include<bits/stdc++.h>
using namespace std;
struct wsl{
	int a,b,c;
	float sj;
}a[200];
bool cmp(wsl x,wsl y){
	if(x.sj>y.sj) return true;
	else return false;
}
int main(){
	int n;
	cin>>n;
	for(int i=1;i<=n;i++){
	    cin>>a[i].a>>a[i].b>>a[i].c;
	    a[i].sj=(a[i].a+a[i].a)*a[i].c/2.0;
	}
    sort(a+1,a+1+n,cmp);
    printf("%.1f",a[1].sj);
	return 0;
}

/**************************************************************
	Problem: 1330
	User: laichenxu
	Language: C++
	Result: Wrong Answer
****************************************************************/