def jiafa(a,b,k):   #a, b为str
    m = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    a0 = 0
    b0 = 0
    a1 = 0
    b1 = 0
    for i in a:
        a1 += 1
        a0 += pow(k,len(a) - a1) * m.index(i)   #10进制的 a
    for i in b:
        b1 += 1
        b0 += pow(k,len(b) - b1) * m.index(i)  # 10进制的 b
    n = a0 + b0
    return shift(int(n),k)

def shift(n,k):     #10进制 int
    s = ''
    m = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    while n != 0:
        i = m[n % k]
        s += i
        n //= k
        a = ''.join(reversed(s))
    return a        #str

def huiwen(n):      #str
    a = n
    c = ''
    for i in n:
        c = i + c
    b = c
    if a == b :
        return 1

def svl(n,k):
    global step
    a = n           #str
    c = ''
    for i in n:
        c = i + c
    b = c           #str
    step += 1
    n = jiafa(a,b,k)
    # print(step)
    if huiwen(n):
        return f'STEP={step}'
    if step == 30:
        return 'Impossible!'
    return svl(n,k)

k = int(input())
n = input()
step = 0
if huiwen(n):
    print(step)
else:
    print(svl(n,k))