#include <cstdlib>
#include <cstdio>
#include <memory>

const int MaxN = 1000010;

char s[MaxN];
int m[12][12];
int p[12];
bool mark[12];
int n, sol;

void compareSolution()
{
	int curr = 0;
	for (int i = 0; i < 10; i++)
		curr += m[ p[i] ][i];

	if (curr < sol) 
		sol = curr;
}

void permutations(int k)
{
	if (k >= 10)
	{
		compareSolution();
	}
	else
	{
		for (int i = 0; i < 10; i++)
			if (!mark[i])
			{
				p[k] = i;
				mark[i] = true;
				permutations(k + 1);
				mark[i] = false;
			}
	}
}

int main()
{
	FILE* inFile = fopen("lepbroj.in", "r");
	FILE* outFile = fopen("lepbroj.out", "w");

	fscanf(inFile, "%d", &n);
	fscanf(inFile, "%s", s);

	memset(m, 0, sizeof(m));
	for (int i = 0; i < n; i++)
		m[s[i] - '0'][i % 10]++;

	for (int i = 0; i < 10; i++)
		for (int j = 0; j < 10; j++)
		{
			m[i][j] = (n / 10) - m[i][j];
			if (1 <= j + 1 && j + 1 <= n % 10) m[i][j]++;
		}

	sol = n + 1;
	memset(mark, false, sizeof(mark));
	permutations(0);

	fprintf(outFile, "%d\n", sol);

	fclose(inFile);
	fclose(outFile);

	return 0;
}