#include<iostream>
#include<cstring>
#include<cmath>
using namespace std;
int main()
{
	int n;
	cin>>n;
	string a,b,c,t="";
	cin>>a>>b;
	int la=a.size();
	int lb=b.size();
	for(int i=0;i<abs(la-lb);i++) t+="0";
	if(la<=lb)a=t+a;
	else if(la>lb) b=t+b;
	int jw=0;
	for(int i=max(la,lb)-1;i>=0;i--)
	{
		int x,y,z;
		if(a[i]>='0'&&a[i]<='9') x=a[i]-'0';else x=a[i]-'a'+10;
		if(b[i]>='0'&&b[i]<='9') y=b[i]-'0';else y=b[i]-'a'+10;
		z=(x+y+jw)%n;
		jw=(x+y+jw)/n;
		if(z>=0&&z<=9) c[i]=(char)(z+'0');
		else c[i]=(char)('a'+z-10);
	}
	if(jw)
	{
		if(jw>=0&&jw<=9) cout<<(char)(jw+'0');
		else cout<<(char)('a'+jw-10);
	}
	for(int i=0;i<max(la,lb);i++) cout<<c[i];
	return 0;
}