function Main(input) {
	var count = 0;
  for(var i = 0; i < input.length; i++){
    var tmp = input.slice(i , i + 1);
    if(tmp == "x"){
       count++;
      if(count >= 8){
         console.log("NO");
        return;
         }
       }
  }
  console.log("YES");
}

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

