#include <bits/stdc++.h>
using namespace std;
#define LL long long
const int N = 1e5 + 10;
const int INF = 0x3f3f3f3f;
int a[1005], b[1005], c[1005];
char s1[1005], s2[1005];
int main()
{
	int n;
	cin >> n >> s1 >> s2;
	int l = strlen(s1);
	for (int i = 0; i < l; i++)
		if (s1[i] >= 'a' && s1[i] <= 'z')
			a[l - i] = s1[i] - 87;
		else
			a[l - i] = s1[i] - 48;
	l = strlen(s2);
	for (int i = 0; i < l; i++)
		if (s2[i] >= 'a' && s2[i] <= 'z')
			b[l - i] = s2[i] - 87;
		else
			b[l - i] = s2[i] - 48;
	l = max(strlen(s1), strlen(s2));
	for (int i = 1; i <= l; i++)
	{
		c[i] += a[i] + b[i];
		c[i + 1] = c[i] / n;
		c[i] %= n;
	}
	if (c[l + 1])
		l++;
	for (int i = l; i > 0; i--)
		if (c[i] > 9)
			cout << char(c[i] + 87);
		else
			cout << c[i];
	return 0;
}