#include<iostream>
using namespace std;
const int N=400;
int n,an,bn,cn,c[N+5];
string a,b;
int de(char x){
	if (x>='0'&&x<='9') return x-'0';
	if (x>='a'&&x<='z') return x-'a'+10;
	return 0;
}
char ge(int x){
	if (x>=0&&x<=9) return x+'0';
	else return 'a'+x-10;
}
int main(){
	cin>>n>>a>>b;
	an=a.length(),bn=b.length();
	for (int i=0;i<an/2;i++) swap(a[i],a[an-i-1]);
	for (int i=0;i<bn/2;i++) swap(b[i],b[bn-i-1]);
	int j=0;
	cn=max(an,bn);
	for (int i=0;i<cn;i++){
		int sum=de(a[i])+de(b[i])+j;
		if (sum>=n) c[i]=sum-n,j=1;
		else c[i]=sum,j=0;
	}if (j) c[cn++]=j;
	for (int i=cn-1;i>=0;i--) cout<<ge(c[i]);
//	cout<<"\n61233236435023623206533054652605436141445054431624165001206254612610161 HAHAHA";
}
/*
in1
7
61233236435023623206533054556061151664533664212063360220665012336055502
63514254143611060216530504450211242243521356
out1
61233236435023623206533054652605436141445054431624165001206254612610161


*/