#include <iostream>
#include <string>
#include <sstream>
using namespace std;

template <typename T>
string to_string(T value) {
    ostringstream os;
    os << value;
    return os.str();
}

bool isPalindrome(string num){//判断是不是回文 
	int left = 0,right=num.length()-1;
	while(left<right){
		if(num[left]!=num[right]){
			return false;
		}
		left++;
		right--;
	}
	return true;
} 

string addReverse(int base,string num){//将给定的字符串与其反转字符串逐位相加
	int n = num.length();
	string reverseNum;
	for(int i=n-1;i>=0;i++){
		reverseNum+=num[i];//给定字符串反转后的字符串 
	}
	int carry = 0;//存储进位
	string sum;//存储逐位相加后的字符串
	for(int i=0;i<n;i++){
		int digitSum=num[i]-'0'+reverseNum[i]-'0'+carry;
		sum+=to_string(digitSum%base);//逐位相加后对应的位 
		carry = digitSum/base;//逐位相加后对应的进位 
	} 
	if(carry>0){
		sum+=to_string(carry);
	} 
	return sum;
} 

int numOfSteps(int base, string num){
	int steps=0;
	while(!isPalindrome(num) && steps<=30){
		num=addReverse(base,num);
		steps++;
	}
	return (steps<=30)?steps:-1;
}

int main(){
	int base;
	string num;
	cin >> base >> num;
	int steps=numOfSteps(base,num);
	if(steps!=-1)
		cout << "STEP=" << steps << endl;
	else
		cout << "Impossible!" << endl;
	return 0;
}