package main
import (
    "fmt"
    "os"
    "bufio"
)

func main() {
    sc := bufio.NewScanner(os.Stdin)
    sc.Scan()
    s := sc.Text()
    rs := []rune(s)
    w := rune('ｗ')
    ma := 0
    suc := 0
    flag := false
    for i := 0; i < len(rs); i++ {
        if rs[i] == w{
            suc++
            if suc > ma && flag{
                ma = suc
            }
        } else {
            suc = 0
            flag = true
        }
    }

    s = ""
    for i := 0; i < len(rs); i++ {
        if rs[i] == w{
            suc ++
            if suc == ma && len(s) > 0 {
                fmt.Printf("%s\n",s)
            }
        }else {
            if suc > 0 && len(s) > 0 {
                s = ""
            }
            suc = 0
            s += string(rs[i])
        }
    }
}