#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int n;
    cin>>n;
    string s;
    cin>>s;
    
    bool a=false,b=false,c=false,d=false;
    int i,j,k;
    int e=0,f=0,g=0,h=0;
    for(i=0;i<n;i++)
    {
        if(s[i]>=48 && s[i]<=57)
            a=true,e=1;
        if(s[i]>=65 && s[i]<=90)
            b=true,f=1;
        if(s[i]>=97 && s[i]<=122)
            c=true,g=1;
        if(s[i]=='!' || s[i]=='@'||s[i]=='$'||s[i]=='%'||s[i]=='^'||s[i]=='&'||s[i]=='*'||s[i]=='('||s[i]==')'||s[i]=='-'||s[i]=='+'||s[i]=='#')
            d=true,h=1;
    }
    int ans=e+f+g+h;
  //  cout<<ans<<endl;
    
    if(ans>=4&&n>=6)
        cout<<"0"<<endl;
    else if(ans>=4 && n<6)
        cout<<6-n<<endl;
    else if(ans<4 && n<6)
        cout<<max(4-ans,6-n)<<endl;
    else if(ans<4 && n>=6)
        cout<<4-ans<<endl;
    return 0;
}