#include<cstdio>
#include<cstring>
#include<cctype>
#include<string>
#include<algorithm>
#include<iostream>
using namespace std;

class input
{
public:
    input& operator >> (string& s)
    {
        char c=' ';s.clear();
        for(;!(c>='a' && c<='z' || c>='0' && c<='9');c=getchar());
        for(;(c>='a' && c<='z' || c>='0' && c<='9');c=getchar()) s+=c;
        return *this;
    }
}in;

const int maxn=210;

int n;
int cnt(0),lima(0),limb(0),a[maxn];
string sa,sb,ans;

int trance(char c)
{
    if(isdigit(c)) return c-'0';
    if(isalpha(c)) return c-'a'+10;
}

char trance2(int i)
{
    if(i<10 && i>=0) return (char)(i+'0');
    if(i<=35 && i>=10) return (char)(i-10+'a');
}

void solve()
{
    for(;lima>=0 && limb>=0;--lima,--limb)
    {
        a[cnt++]+=trance(sa[lima])+trance(sb[limb]);
        a[cnt]+=a[cnt-1]/n; a[cnt-1]%=n;
    }
    if(lima) for(;lima>=0;--lima)
    {
        a[cnt++]+=trance(sa[lima]);
        a[cnt]+=a[cnt-1]/n; a[cnt-1]%=n;
    }
    if(limb) for(;limb>=0;--limb)
    {
        a[cnt++]+=trance(sb[limb]);
        a[cnt]+=a[cnt-1]/n; a[cnt-1]%=n;
    }
    if(a[cnt]) ++cnt;
    for(int i=cnt-1;i>0;--i)
    {
        putchar(trance2(a[i]));
    }
}

int main()
{
    freopen("madition.in","r",stdin);
    freopen("madition.out","w",stdout);

    cin>>n; in>>sa>>sb;
    lima=sa.length(),limb=sb.length();
    solve();
    cout<<ans<<endl;
    
    fclose(stdin); fclose(stdout);
    return 0;
}