function _0xe35c(d, e, f) {

    var g = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ+/".split("");
    var h = g.slice(0, e);
    var i = g.slice(0, f);
    var j = d.split("").reverse().reduce(function (a, b, c) {
        if (h.indexOf(b) !== -1) return a += h.indexOf(b) * (Math.pow(e, c))
    }, 0);
    var k = "";
    while (j > 0) {
        k = i[j % f] + k;
        j = (j - (j % f)) / f
    }
    return k || "0"
}
var d = "57"
var e = "8"
var f = "10"
document.write(_0xe35c(d, e, f))

##################################################
### python
##################################################
from functools import reduce
d = '57'
e = 8
f = 10
def _0xe35c(d, e, f) :
    g = list("0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ+/")
    h = g[0:e]
    i = g[0:f]
    listd = list(d)[::-1]
    def red(a,b,c=0):
            indx = h.index(b)
            if indx!=-1:
                wyn = int(float(indx) *(math.pow(int(e),c)))
                a+=(wyn)
                return a
    j = reduce(red,listd,0)
    k = ''
    while j>0:
        k = i[j % f] + k
        j = (j - (j % f)) / f
    return k if k else "0"
ax=_0xe35c(d, e, f)