'use strict'

function Main(input) {
  const S = input.split("")
  const remaining = 15 - S.length

  let win = S.filter(x => x === "o").length
  
  if (win + remaining >= 8) {
    console.log("YES")
  } else {
    console.log("NO")
  }
}

Main(require("fs").readFileSync("/dev/stdin", "utf8").trim())
