include <iostream>

using namespace std;

int main()
{
int dem=0,a[100],n;
cin>>n;
for(int i=1;i<=n;i++)
{
cin>>a[i];
}
for(int i=1;i<=n;i++)
{
for(int j=1;j<=n;j++)
{
if(a[j]==a[i]&&i!=j ) dem++;
}

}
cout<<"So cap so bang nhau la: "<<dem/2;
}