#include<stdio.h>#include<string>#include<cmath>#include<iostream>using namespace std;int main(){  string a,b;  int tag,radix;  int anum,bnum;  //freopen("1010-in.txt","r",stdin);  //freopen("1010-out.txt","w",stdout);    while(cin>>a>>b>>tag>>radix)  {     anum=bnum=0;     string temp;     if(tag==1)     {        int index=0;        for(int j=a.length()-1;j>=0;j--)        {           anum+=(a[j]>=‘a‘?a[j]-‘a‘+10:a[j]-‘0‘)*pow(radix*1.0,index);           index++;        }          temp=b;     }else     {        int index=0;        for(int j=b.length()-1;j>=0;j--)        {           anum+=(b[j]>=‘a‘?b[j]-‘a‘+10:b[j]-‘0‘)*pow(radix*1.0,index);           index++;        }         temp=a;     }     //printf("anum=%d\n",anum);       char max=0;     //get max num;      for(int i=0;i<temp.length();i++)     {       if(temp[i]>max)         max=temp[i];     }     int maxNum=(max>=‘a‘?max-‘a‘+10:max-‘0‘);     bool flag=false;     int ind;          //printf("maxNum=%d\n",maxNum);     long long  maxRadix=0xffffffff;     maxRadix=maxRadix>>1;     for(ind=maxNum+1;ind<=maxRadix;ind++)     {        bnum=0;        int index=0;        for(int j=temp.length()-1;j>=0;j--)        {           bnum+=(temp[j]>=‘a‘?temp[j]-‘a‘+10:temp[j]-‘0‘)*pow(ind*1.0,index);           index++;        }        if(bnum>anum)           break;        //printf("%d ",bnum);        if(anum==bnum)        {            flag=true;            break;        }     }          if(flag)     {        printf("%d\n",ind==1?ind+1:ind);     }     else     {         printf("Impossible\n");     }  }      }