Kata

Our standard numbering system is base-10, that uses digits 0 through 9. Binary is base-2, using only 1s and 0s. And hexadecimal is base-16, using digits 0 to 9 and A to F. A hexadecimal F has a base-10 value of 15.

Base-64 has 64 individual characters ("digits") which translate to the base-10 values of 0 to 63. These are (in ascending order):

ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/

(so A is equal to 0 and / is equal to 63)

Task

Complete the method that will take a base-64 number (as a string) and output its base-10 value as an integer.

Examples

"/"   -->  63
"BA"  -->  64
"BB"  -->  65
"BC"  -->  66
"WIN" -->  90637