Return one cell value based on month in another cell

  I have 3 cells
    A1=5
    A2=7
    A3= 15/01/2015
    C1 = empty cell

what i need to be shown in the empty cell (C1) is : if the month in A3 is Jan ... then return A1 value (5) but if the month in A3 is Feb ... then return A2 value (7)

Thanks in advance for the answers