I already programmed the solution of your assignment. I'm a professional software developer, have a look at my profile.
Just to proof to you, here is the first part of the solution string that will be displayed in the text box (freelancer.com does not allow me more characters in my proposal.)
A1w2, A1w4, A1w6, A1w8, A1w10, A1x2, A1x4, A1x6, A1x8, A1x10, A1y2, A1y4, A1y6, A1y8, A1y10, A1z2, A1z4, A1z6, A1z8, A1z10, A3w2, A3w4, A3w6, A3w8, A3w10, A3x2, A3x4, A3x6, A3x8, A3x10, A3y2, A3y4, A3y6, A3y8, A3y10, A3z2, A3z4, A3z6, A3z8, A3z10, A5w2, A5w4, A5w6, A5w8, A5w10, A5x2, A5x4, A5x6, A5x8, A5x10, A5y2, A5y4, A5y6, A5y8, A5y10, A5z2, A5z4, A5z6, A5z8, A5z10, B1w2, B1w4, B1w6, B1w8, B1w10, B1x2, B1x4, B1x6, B1x8, B1x10, B1y2, B1y4, B1y6, B1y8, B1y10, B1z2, B1z4, B1z6, B1z8, B1z10, B3w2, B3w4, B3w6, B3w8, B3w10, B3x2, B3x4, B3x6, B3x8, B3x10, B3y2, B3y4, B3y6, B3y8, B3y10, B3z2, B3z4, B3z6, B3z8, B3z10, B5w2, B5w4, B5w6, B5w8, B5w10, B5x2, B5x4, B5x6, B5x8, B5x10, B5y2, B5y4, B5y6, B5y8, B5y10, B5z2, B5z4, B5z6, B5z8, B5z10, C1w2, ... and so on (freelancer.com does not allow me more characters..)