text: #include <bits/stdc++.h>
  #define D(x) cout << #x " = " << (x) << endl
  #define endl '\n'
  
  using namespace std;
  
  int main()
  {
      ios_base::sync_with_stdio(false);
      cin.tie(NULL);
      int a, b, c;
      while (cin >> a >> b >> c)
      {
          int m1 = b - a,
              m2 = c - b;
  
          if (m2 > m1)
              cout << ":)"  << endl;
          else if (m2 < m1)
              cout << ":(" << endl;
          else
          {
              if (m1 <= 0)
                  cout << ":(" << endl;
              else
                  cout << ":)" << endl;
          }
      }
      return 0;
  }
  