C++ :

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<queue>
#include<iostream>
#include<stack>
#include<algorithm>
#include<vector>
#include<iterator>
#include<map>
#include<set>
#include<cmath>
#include<iostream>
#include<string>
using namespace std;
string tr(int x,int y,string s)
{
    string res="";
    int sum=0;
    for(int i=0;i<s.length();++i)
    {
        if(s[i]=='-')
            continue;
        if(s[i]>='0' && s[i]<='9')
            sum=sum*x+s[i]-'0';
        else
            sum=sum*x+s[i]-'a'+10;
    }
    while(sum)
    {
        char tmp=sum%y;
        sum/=y;
        if(tmp<=9)
            tmp+='0';
        else
            tmp=tmp-10+'a';
        res=tmp+res;
    }
    if(res.length()==0)
        res="0";
    if(s[0]=='-')
        res='-'+res;
    return res;
}
inline int mx(int a,int b)
{
    return a>b?a:b;
}
inline int mi(int a,int b)
{
    return a<b?a:b;
}
inline int abs1(int a)
{
    return a>0?a:-a;
}
int main()
{
    string an;
    stack<char> s;
    int a,b;
    while(1)
    {
        string s;
        scanf("%d ",&a);
        cin>>s;
        if(a==0 && s=="0")
            break;
        /*while(!s.empty())
            s.pop();
        int k=0;
        while(b)
        {
            int w=b%a;
            if(w<10)
                s.push(w+'0');
            else
                s.push(w-10+'a');
            b/=a;
        }
        while(!s.empty())
        {
            char ans=s.top();
            s.pop();
            printf("%c",ans);
        }
        printf("\n");*/
        an=tr(10,a,s);
        cout<<an<<endl;
    }
 
    return 0;
}