#include<iostream>
    #include<cstdio>
    #include<algorithm>
    #include<cstring>
    using namespace std;
    int wjh()
    {
    freopen("madition.in","r",stdin);
    freopen("madition.out","w",stdout);
    int n;
    cin>>n;
    const char a[36]={'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
    string sa,sb;
    cin>>sa>>sb;
    int aa[10005]={0},bb[10005]={0};
    int wa=sa.length(),wb=sb.length();
    for(int i=0;i<wa;i++)
    {
    if(sa[i]>='0'&&sa[i]<='9')
    aa[wa-i-1]=sa[i]-'0';
    else
    aa[wa-i-1]=sa[i]-'a'+10;
    }
    for(int i=0;i<wb;i++)
    {
    if(sb[i]>='0'&&sb[i]<='9')
    bb[wb-i-1]=sb[i]-'0';
    else
    bb[wb-i-1]=sb[i]-'a'+10;
    }
    if(wa<wb)
    wa=wb;
    for(int i=0;i<wa;i++)
    aa[i]+=bb[i];
    for(int i=0;i<wa;i++)
    {
    if(aa[i]>=n)
    {
    aa[i]-=n;
    aa[i+1]+=1;
    }
    }
    if(aa[wa]!=0)
    wa++;
    for(int i=wa-1;i>=0;i--)
    cout<<a[aa[i]];
    return 0;
    }
    int W=wjh();
    int main()
    {;}