修正一下

#include <bits/stdc++.h>
using namespace std;
int main ( )
{
int n ;
cin >> n ;
if ( n > 0 )
{
cout << "positive" ;
}
if ( n < 0 )
{
cout << "negative" ;
}
if ( n == 0 )       //else cout << "zero" ;
{                  //...
cout << "zero" ;  //... ...
}                //... ... ...
}