find height of generic tree represented by parent array

#include <bits/stdc++.h>

using namespace std;

int height(int a[], int n){
    int curr_height, max_height=-1,i,j;
    for(i=0; i<n; i++){
        curr_height=0; j=i;
        while(a[j]!=-1)
        {
            curr_height++;
            j=a[j];
        }
        if(curr_height > max_height)
           max_height = curr_height;
    }
return max_height;
}




int main()
{
   int a[9] = {-1, 0, 1,6,6,0,0,2,7};
   cout<<height(a,9);
    return 0;
}