#include<bits/stdc++.h>
using namespace std;
const int N=2010;
char a[N],b[N];
int c[N];
int main()
{
	int B;
	cin>>B;
	cin>>a>>b;
	int m=strlen(a),n=strlen(b);
	reverse(a,a+m);
	reverse(b,b+n);
	int lenc=max(n,m)+1;
	for(int i=0,t=0;i<=lenc;i++)
	{
		int ta=0;
		if(a[i]>='0'&&a[i]<='9') ta=a[i]-'0';
		else if(a[i]>='A'&&a[i]<='Z') ta=a[i]-'A'+10;
		
		int tb=0;
		if(b[i]>='0'&&b[i]<='9') tb=b[i]-'0';
		else if(b[i]>='A'&&b[i]<='Z') tb=b[i]-'A'+10;
		
		int k=t+ta+tb;
		c[i]=k%B;
		t=k/B; 
		//cout<<c[i]<<endl;
	}
	//cout<<lenc<<endl;
	while(lenc&&c[lenc]==0) lenc--;
	//cout<<lenc;
	for(int i=lenc;i>=0;i--)
	{
		if(c[i]>=10) cout<<char(c[i]-10+'A');
		else cout<<c[i];
	}
	return 0;
}