"use strict";

// read lines from stdin
const input = require("fs")
  .readFileSync("/dev/stdin", "utf8").trim();

let win = 0;

for (let i = 0; i < input.length; i++) {
  if (input.charAt(i) === "o") {
    win++;
  }
}

console.log(win + (15 - input.length) >= 8 ? "YES" : "NO");
