'use strict';

function main(stdin) {
  const input = stdin.split('').map(s => s === 'o' ? 1 : 0);
  const wins = input.filter(s => s).length;
  const rest = 15 - input.length;
  if (wins + rest < 8) {
    console.log('NO');
  } else {
    console.log('YES');
  }
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));