def radixes(number,num_radix,out_radix):
    raxid=0
    raxid10= int(number, num_radix)
    if(out_radix == 2):
        raxid = bin(raxid10)
    elif(out_radix == 8):
        raxid = oct(raxid10)
    elif(out_radix == 16):
        raxid = hex(raxid10)
    elif(out_radix == 10):
        raxid = raxid10
        return raxid
    return raxid[2:]
def h(number):
    if(str(number) == str(number)[::-1]):
        return True
    else:
        return False
n = int(input())
m = input()
s = radixes(m,n,10)
for i in range(30):
    if h(s):
        print('STEP=' + str(i))
        exit()
    s += int(str(s)[::-1])
print('Impossible!')