Kevin knows it is not ideal to retire with a mortgage, but he has always rented and is now ready to buy a condo in downtown Montreal, five years before he retires. He has visited several condos and will be making an offer on December $1,2023.$ To date, he has saved $$15,000$ for which he will use as part of the downpayment along with the maximum he can withdraw from his Registered Retirement Savings Account $($RRSP$)$ under the Home Buyer's Plan $($HBP$).$ He currently has $$455,942$ in his RRSP$.$ What would be the minimum conventional mortgage Kevin could assume?