It should be at least 1.5 ampere or the fuse will melt. That's all that can happen. Both 5 and 13 are greater than 1.5, but 3 is also. So it will be quite fine.
I have a Sony Vaio adapter which reads:
input 1.5 amperes
output 4.7 amperes
My supplier told me that a suitable power plug (which connects the adapter with the electricity outlet) should be 3 amperes.
But I own two that read 5 amperes and 13 amperes.
Would any of them cause technical issues in the adapter or the laptop if used?