#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int nx=1e5+5;
ll n, x[nx], y[nx];
struct myvector
{
ll x, y;
myvector(ll x, ll y): x(x), y(y){}
};
ll cross(myvector a, myvector b)
{
return a.x*b.y-a.y*b.x;
}
ll mydiv(ll a, ll b)
{
if (b==0) return 1;
else return a/b;
}
int main()
{
cin.tie(NULL)->sync_with_stdio(false);
cin>>n;
for (int i=1; i<=n; i++) cin>>x[i]>>y[i];
if (n<=2) return cout<<-1, 0;
myvector v1=myvector(x[2]-x[1], y[2]-y[1]), v2=myvector(x[3]-x[1], y[3]-y[1]);
if (cross(v1, v2)==0) return cout<<-1, 0;
cout<<abs(cross(v1, v2));
}
/*
3
1 2
4 1
0 0
*/
