Pine valley had $150,000$shares of stock issued and outstanding January $1,2021$ on July $1,2021,0$an additional $25,000$ shares of common stock were issued for cash. Pine valley also had unexercised stock options to purchase $20,000$ shares of common stock at $$15$ per share outstanding at the beginning and end of $2021.$ The average market price of pine valley's common stock was $$20$ in $2021.$ What number of shares should be used in computing diluted earnings per share for the ended December $31,2021?$