Heidi has finally found the mythical Tree of Life – a legendary combinatorial structure which is said to contain a prophecy crucially needed to defeat the undead armies.

On the surface, the Tree of Life is just a regular undirected tree well-known from computer science. This means that it is a collection of n points (called vertices), some of which are connected using n - 1 line segments (edges) so that each pair of vertices is connected by a path (a sequence of one or more edges).

To decipher the prophecy, Heidi needs to perform a number of steps. The first is counting the number of lifelines in the tree – these are paths of length 2, i.e., consisting of two edges. Help her!

Input

The first line of the input contains a single integer n – the number of vertices in the tree (1 ≤ n ≤ 10000). The vertices are labeled with the numbers from 1 to n. Then n - 1 lines follow, each describing one edge using two space-separated numbers a b – the labels of the vertices connected by the edge (1 ≤ a < b ≤ n). It is guaranteed that the input represents a tree.

Output

Print one integer – the number of lifelines in the tree.

Examples

Input

4
1 2
1 3
1 4


Output

3

Input

5
1 2
2 3
3 4
3 5


Output

4

Note

In the second sample, there are four lifelines: paths between vertices 1 and 3, 2 and 4, 2 and 5, and 4 and 5.
#include <bits/stdc++.h>
using namespace std;
template <typename T>
T gcd(T first, T second) {
  while (second > 0) {
    first %= second;
    swap(first, second);
  }
  return first;
}
template <class T>
T lcm(T a, T b) {
  return a / gcd(a, b) * b;
}
template <class _T>
inline _T sqr(const _T &first) {
  return first * first;
}
template <class _T>
inline string tostr(const _T &a) {
  ostringstream os("");
  os << a;
  return os.str();
}
const long double PI = 3.1415926535897932384626433832795L;
template <typename T>
inline void input(T &a) {
  static int ed;
  a = 0;
  while (!isdigit(ed = getchar()) && ed != '-') {
  }
  char neg = 0;
  if (ed == '-') {
    neg = 1;
    ed = getchar();
  }
  while (isdigit(ed)) {
    a = 10 * a + ed - '0';
    ed = getchar();
  }
  if (neg) a = -a;
}
template <typename T = int>
inline T nxt() {
  T res;
  input(res);
  return res;
}
void myassert(bool v) { assert(v); }
mt19937 generator;
bool check(int v) {
  if (v < 2) return false;
  for (int i = 2; i * i <= v; ++i) {
    if (v % i == 0) {
      return false;
    }
  }
  return true;
}
long long pw(long long a, long long n, long long m) {
  long long res = 1;
  while (n) {
    if (n & 1ll) {
      res = res * a % m;
    }
    a = a * a % m;
    n >>= 1;
  }
  return res;
}
long long inv(long long a, long long p) {
  long long res = 1;
  while (a > 1) {
    res = res * (p - p / a) % p;
    a = p % a;
  }
  return res;
}
void solve(int test) {
  int n = nxt();
  int d[n];
  memset((d), 0, sizeof(d));
  for (int i = 0; i < (int)(n - 1); ++i) {
    int u = nxt() - 1;
    int v = nxt() - 1;
    d[u]++;
    d[v]++;
  }
  long long ans = 0;
  for (int i = 0; i < (int)(n); ++i) {
    ans += d[i] * 1ll * (d[i] - 1) / 2;
  }
  cout << ans << "\n";
}
int main(int argc, char **argv) {
  int t = 1;
  int c = 0;
  while (t--) {
    solve(++c);
  }
  return 0;
}
