求助，

#include<bits/stdc++.h>
using namespace std;
int jinz; 
int ans;
string k;
string ss;
string gjd(string s1,string s2,int jz)
{
	cin>>s1>>s2;
	string s3;
	int a[510],b[510],c[510];
	memset(a,0,sizeof(a));
	memset(b,0,sizeof(b));
	memset(c,0,sizeof(c));
	int len=max(s1.length(),s2.length());
	for (int i=s1.length()-1,j=1;i>=0;i--,j++)
        a[j]=s1[i]-'0';
    for (int i=s2.length()-1,j=1;i>=0;i--,j++)
        b[j]=s2[i]-'0';
	for(int i=1;i<=len;i++)
	{
		c[i]+=a[i]+b[i];
		c[i+1]=c[i]/jz;
		c[i]%=jz;
	}
	if(c[len+1])
	{
		len++;
	}
	for(int i=len;i>=1;i--)
	{
		int point=0;
		s3[point]=c[i]+'0';
		point++;
	}
	return s3;
}

bool hw(string s)
{
	int len=s.length();
	for(int i=0;i<len;i++)
	    if(s[i]!=s[len-1-i])return 0;
	return 1;
}

int main()
{
    cin>>jinz>>k;
    ss=k;
    for(int i=1;i<=30;i++)
    {
    	ans++;
    	string s=ss;
    	reverse(ss.begin(),ss.end());
    	ss=gjd(ss,s,jinz);
    	if(hw(ss))
    	{
    		cout<<"STEP="<<ans;
    		return 0;
		}
	}
	cout<<"Impossible!";
	return 0;
}