```go
package main

import (
	"fmt"
)

func main() {
	var k int64
	fmt.Scan(&k)

	lo, hi := int64(1), int64(100)
	for lo < hi {
		mid := (lo + hi + 1) / 2
		p := int64(1)
		overflow := false
		for i := 0; i < 10; i++ {
			p *= mid
			if p > k {
				overflow = true
				break
			}
		}
		if overflow || p > k {
			hi = mid - 1
		} else {
			lo = mid
		}
	}
	x := lo

	c := 0
	for ; c <= 10; c++ {
		prod := int64(1)
		overflow := false
		for i := 0; i < c; i++ {
			prod *= (x + 1)
			if prod > k {
				overflow = true
				break
			}
		}
		if !overflow {
			for i := c; i < 10; i++ {
				prod *= x
				if prod > k {
					overflow = true
					break
				}
			}
		}
		if overflow || prod >= k {
			break
		}
	}

	s := "codeforces"
	res := make([]byte, 0, 10*int(x+2))
	for i := 0; i < 10; i++ {
		cnt := x
		if i < c {
			cnt = x + 1
		}
		for j := int64(0); j < cnt; j++ {
			res = append(res, s[i])
		}
	}

	fmt.Println(string(res))
}
```