#include<bits/stdc++.h>

using namespace std;

int rand(int a, int b)
{
    return a + rand()%(b-a+1);
}
// returns true if more than 3 connections,,binary tree..
bool count_connections(vector <pair <int, int > v, int m)
{
   int n = v.size();
   int count{0};
   for(int i =0 ; i < n ; i++)
   {
       if(v.at(i).first == m || v.at(i).second == m)
         count++;
   }
   if (count > 3)
    return false;
   return true;
}

int main(int argc, char * argv[])
{
    srand(atoi(argv[1]));
    vector < pair <int, int> > v;
    int n = rand(2, 20);
    printf("%dn", n);
    for(int i =2; i <= n; ++i)
    {
         v.push_back(make_pair(rand(1, i-1), i));
        if(count_connections(v, i))
        printf("%d %dn", rand(1, i-1), i);
    }
}

```````
I think it has something to do with use of vector as first argument..I am not sure what.

simple_tree_gen.cpp:10:57: error: template argument 1 is invalid
 bool count_connections(vector <pair <int, int > &v, int m)
                                                         ^
simple_tree_gen.cpp:10:57: error: template argument 2 is invalid
simple_tree_gen.cpp:10:57: error: template argument 1 is invalid
simple_tree_gen.cpp:10:57: error: template argument 2 is invalid
simple_tree_gen.cpp:10:57: error: template argument 1 is invalid
simple_tree_gen.cpp:10:57: error: template argument 2 is invalid
simple_tree_gen.cpp:10:57: error: template argument 1 is invalid
simple_tree_gen.cpp:10:57: error: template argument 2 is invalid
simple_tree_gen.cpp:10:24: error: invalid template-id
 bool count_connections(vector <pair <int, int > &v, int m)
                        ^~~~~~
simple_tree_gen.cpp:10:58: error: missing template arguments before ‘)’ token
 bool count_connections(vector <pair <int, int > &v, int m)
                                                          ^
simple_tree_gen.cpp: In function ‘int main(int, char**)’:
simple_tree_gen.cpp:33:34: error: ‘count_connections’ cannot be used as a function
         if(count_connections(v, i))