text: #include<iostream>
  using namespace std;
  
  int main(){
  	int temp1, temp2, temp3;
  	cin >> temp1 >> temp2 >> temp3;
  	
  	if(temp2 < temp1 && temp3 >= temp2) cout << ":)" << endl;
      else if(temp2 > temp1 && temp3 <= temp2) cout << ":(" << endl;
      else if(temp2 > temp1 && temp3 > temp2 && (temp3 - temp2) < (temp2 - temp1)) cout << ":(" << endl;
      else if(temp2 > temp1 && temp3 > temp2 && (temp3 - temp2) >= (temp2 - temp1)) cout << ":)" << endl;
      else if(temp2 < temp1 && temp3 < temp2 && (temp2 - temp3) < (temp1 - temp2)) cout << ":)" << endl;
      else if(temp2 < temp1 && temp3 < temp2 && (temp2 - temp3) >= (temp1 - temp2)) cout << ":(" << endl;
      else if(temp2 == temp1 && temp3 > temp2) cout << ":)" << endl;
      else if(temp2 == temp1 && temp3 < temp2) cout << ":(" << endl;
      else cout << ":(" << endl;
  	return 0;
  }
  