#include <bits/stdc++.h>

using namespace std;

typedef long long lol;
typedef pair<int,int> pii;
typedef map<int,int> mii;

#define pf printf
#define sf scanf
#define pause system("pause")
#define pmin int,vector<int>,greater<int>
#define checkBit(n,p) (bool)(n&(1<<p))
#define setBit(n,p) (n|=(1<<p))
#define resetBit(n,p) (n&=~(1<<p))
#define toggleBit(n,p) (n^=1<<p)
#define mp make_pair
#define pb push_back
#define PI acos(-1.0)
#define sqr(x) ((lol)x*x)
#define gcd(x,y) __gcd((lol)abs(x),(lol)abs(y))
#define lcm(x,y) (abs(x)/__gcd((lol)abs(x),(lol)abs(y))*abs(y))
#define logB(val,base) log(double(val))/log(double(base))*/
#define memval(arr,val) memset(arr,val,sizeof(arr))

string numToString(lol num){string word;stringstream ss;ss<<num;ss>>word;return word;}
lol stringToNum(string word){lol num;stringstream ss;ss<<word;ss>>num;return num;}
template<typename t>void setDigit(t &num,int pos,int digit){string word=numToString(num);
while(word.length()<=pos)word='0'+word;word[word.length()-pos-1]='0'+digit;num=stringToNum(word);}

int dirK[8][2] = {{-2,1},{-1,2},{1,2},{2,1},{2,-1},{1,-2},{-1,-2},{-2,-1}};
int dir8[8][2] = {{-1,0},{-1,1},{0,1},{1,1},{1,0},{1,-1},{0,-1},{-1,-1}};
int dir4[4][2] = {{-1,0},{0,1},{1,0},{0,-1}};
int month[] = {31,28,31,30,31,30,31,31,30,31,30,31};

/*============================================================================//
                   it always seems impossible until it’s done
//============================================================================*/

int get(char ch)
{
    if(ch >='0'&&ch<='9')
    {
        return 0;
    }
    else if(ch>='a'&&ch<='z')
    {
        return 1;
    }
    else if(ch>='A'&&ch<='Z')
    {
        return 2;
    }
    else if(ch=='!'||ch=='@'||ch=='#'||ch=='$'||ch=='%'||ch=='^'||ch=='&'||ch=='*'||ch=='*'||ch=='('||ch==')'||ch=='-'||ch=='+')
    {
        return 3;
    }
    return -1;
}

int main()
{
    ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
    //freopen("00_input.txt","r",stdin);freopen("00_output.txt","w",stdout);
    //pf("Hello World!\n");
    /*int t,i;
    sf("%d",&t);
    for(i=0;i<t;i++)
    {
    }*/
    int i,num,need;
    string word;

    cin >> num;

    cin >> word;
    set<int> st;

    for(i=0;i<word.length();i++)
    {
        num = get(word[i]);
        if(num!=-1)
        {
            st.insert(num);
        }
    }
    num = 6 - word.size();
    need = 4 - st.size();
    cout << max(need,num) << endl;
}