# Untitled

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```    #include <bits/stdc++.h>
#define endl '\n'
#define maxn 105
#define For(i,a,b) for ( int i = a; i <= b; i++ )
#define MOD 100000000000007

using namespace std;
int x[maxn],n,y[maxn];
double p,s,ans = -MOD,a,b,c,r;
void inp()
{
cin >> n;
For(i,1,n)
cin >> x[i] >> y[i];
}

bool check(double a, double b, double c)
{
if (a*a >= b*b + c*c) return true;
if (a*a < b*b + c*c) return false;

}
void swa(int a, int b, int c)
{
if (b < c) swap(b,c);
if (a < b) swap(a,b);
if (a < c) swap(a,c);
}
double Tinh(int i, int j)
{
double res = sqrt((x[i] - x[j])*(x[i] - x[j]) + (y[i] - y[j])*(y[i] - y[j]));
return res;
}
double Rad(double a, double b, double c)
{
p = (a + b + c)/2;
s =sqrt(p*(p-a)*(p-b)*(p-c));
double res = (a*b*c)/(4*s);
return res;
}
void solve()
{
For(i,1,n-2)
For(j,i+1,n-1)
For(k,j+1,n)
{
a = Tinh(i,j); b = Tinh(j,k); c = Tinh(i,k);
swa(a,b,c);
if(check(a,b,c)) r = a/2;
ans = max(ans,r);
}
cout << setprecision(3) << fixed << ans;
}
int main()
{
ios_base:: sync_with_stdio(0);
cin.tie(0);
if(fopen("bai1.inp","r")){
freopen("bai1.inp","r",stdin);
}
inp();
solve();
}
```