#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
const int MAXN = 200;
int _w;

int n;
char s[MAXN];

const char *s1 = "0123456789";
const char *s2 = "abcdefghijklmnopqrstuvwxyz";
const char *s3 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
const char *s4 = "!@#$%^&*()-+";

bool check1( char c ) {
	for( const char *p = s1; *p; ++p )
		if( *p == c ) return true;
	return false;
}
bool check2( char c ) {
	for( const char *p = s2; *p; ++p )
		if( *p == c ) return true;
	return false;
}
bool check3( char c ) {
	for( const char *p = s3; *p; ++p )
		if( *p == c ) return true;
	return false;
}
bool check4( char c ) {
	for( const char *p = s4; *p; ++p )
		if( *p == c ) return true;
	return false;
}

int main() {
	_w = scanf( "%d%s", &n, s );
	bool c1 = 0, c2 = 0, c3 = 0, c4 = 0;
	for( int i = 0; i < n; ++i ) {
		c1 |= check1( s[i] );
		c2 |= check2( s[i] );
		c3 |= check3( s[i] );
		c4 |= check4( s[i] );
	}
	int ans = 6 - n;
	int cnt = !c1 + !c2 + !c3 + !c4;
	printf( "%d\n", max(ans, cnt) );
	return 0;
}