write a go solution for Description:
Karl likes Codeforces and subsequences. He wants to find a string of lowercase English letters that contains at least k subsequences codeforces. Out of all possible strings, Karl wants to find a shortest one.

Formally, a codeforces subsequence of a string s is a subset of ten characters of s that read codeforces from left to right. For example, codeforces contains codeforces a single time, while codeforcesisawesome contains codeforces four times: codeforcesisawesome, codeforcesisawesome, codeforcesisawesome, codeforcesisawesome.

Help Karl find any shortest string that contains at least k codeforces subsequences.

Input Format:
The only line contains a single integer k (1<=k<=10^16).

Output Format:
Print a shortest string of lowercase English letters that contains at least k codeforces subsequences. If there are several such strings, print any of them.

Note:
None. Output only the code with no comments, explanation, or additional text.