(defvar N)
(setq N 31)
(defvar sum)
(setq sum 0)
(defvar mon)

(loop for mon from 1 to 12 do
    (case mon
        ( 1 (setq N 31) )
        ( 2 (setq N 28) )
        ( 3 (setq N 31) )
        ( 4 (setq N 30) )
        ( 5 (setq N 31) )
        ( 6 (setq N 30) )
        ( 7 (setq N 31) )
        ( 8 (setq N 31) )
        ( 9 (setq N 30) )
        ( 10 (setq N 31) )
        ( 11 (setq N 30) )
        ( 12 (setq N 31) )
    )
    (loop for i from 1 to N do
        (if (eq mon (+ (floor i 10) (mod i 10))) (incf sum)))

)
(format 't "~d~%" sum)