I am trying to sum alphanumeric cells, the following cells have:

A1= Mon, A2= blank
B1= Tue, B2= 3
C1= Wed, C2= 4a
D1=Thur, D2= blank
E1= Fri, E2= 3s
F1= Sat, F2= 1a
G1= Sun, G2= 2s
H1= Mon, H2= 4
i1= Tue, i2= 7s
J1=Wed, J2= blank
K1=Thur, K2= blank
L1=Fri, L2= 1
M1=Sat, M2= 8
N1=Sun, N2= blank
O1=Mon, O2= 6a

"a" represents Annual Leave, "s" represents Sick Leave, and a number
represents Over Time. The numbers, alphanumeric numbers, and blank
cells can randomly be in any day of the week cell/column. My goal is
to sum cells that have "a" and sum cells that have "s" and sum cells
that have a number seperately, example...

A4 = "Over Time"
A5 = "16" (3 + 4 + 1 + 8 = 16)
B4 = "Annual Leave"
B5 = "11" (4a + 1a + 6a = 11)
C4 = "Sick Leave"
C5 = "12" (3s + 2s + 7s = 12)

Can anyone please help me...?
Sincerely,
JimmyD