Find the Telephone

Problem Number: 
10 921
Type of Problem: 
Single Output Problem
Problem Category: 
Volume 109 (10,900-10,999)
Input: 
0
0
0
Critical Input: 
Random Input: 
Problem Description Link: 
https://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&category=1…
Problem Id: 
10921