#include<stdio.h>
int f(char c)
{
	if ('0' <= c && c <= '9')
		return c - '0';
	else
		return c - 'A' + 10;
}
int main()
{
	int n;
	scanf("%d", &n);
	int i, j;
	char v[16];
	long long int ans;
	long long int r, p;
	for (j = 0; j < n; j++)
	{
		scanf("%s", v);
		p = 0;
		for (i = 0; v[i] != '\0'; i++)
			if (p < f(v[i]))
				p = f(v[i]);
		p++;
		r = 0;
		for (i = 0; v[i] != '\0'; i++)
			r = p * r + f(v[i]);
		if (j > 0)
		{
			if (ans > r)
				ans = r;
		}
		else
			ans = r;
	}
	printf("%lld\n", ans);
	return 0;
}