Data Validation - how to ignore cells with "0" or "-"

Data validation is required but combined with the formula in C1 was the best I could come up. I tried various configurations of IF(OR, IF(AND conditional statement formulas but failed to come up with one that would work. The data entry into cells A1 and B1 will probably be manual and I simply need a means of blocking entry of non-zero values into both cells. I also would prefer to avoid VBA as this spreadsheet will be used and re-used by many people over time with rows and columns being added perhaps. Can you provide a formula in C1, and perhaps conditional formatting for A1 and B1 that will work?

Thanks for your input. David

I meant Data Validation is NOT required.... sorry.