#include <stdio.h>
#include <stdlib.h>

int N;

long long ReverseN(long long x)
{
    int y = 0;
    while (x > 0)
    {
        y *= N;
        y += x % N;
        x /= N;
    }
    return y;
}

long long PlusN(long  long a, long long b)
{
    int c = 0, t = 0, w = 1;
    while (a > 0 || b > 0 || t > 0)
    {
        int i = a % N, j = b % N;
        c += (i + j + t) % N * w;
        t = (i + j + t) / N;
        a /= N, b /= N;
        w *= N;
    }
    return c;
}

int main(void)
{
    char digits[100];
    scanf("%d%s", &N, digits);
    long long M = strtoll(digits, NULL, N);
    int s = 0;
    while (M != ReverseN(M))
    {
        M = PlusN(M, ReverseN(M));
        s++;
        if (s > 30)
        {
            printf("Impossible!");
            return 0;
        }
    }
    printf("STEP=%d", s);
    return 0;
}