#include<bits/stdc++.h> using namespace std; int main() { string w="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; string a, b; int N,x[100],y[100]; cin>>N>>a>>b; while(a.length()<b.length()) a='0'+a; while(b.length()<a.length()) b='0'+b; a='0'+a; b='0'+b; for(int i=a.length()-1;i>=0;i--) { x[i]=w.find(a[i],0); y[i]=w.find(b[i],0); } for(int i=a.length()-1;i>=0;i--) { x[i]=x[i]+y[i]; if(x[i]>=N) for(int k=i;x[k]>=N;k--) { x[k]=x[k]-N; x[k-1]++; } a[i]=w[x[i]]; } while(a[0=='0']) a.erase(0,1); cout<<(a.length()==0?"0":a)<<endl; return 0; }