process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});

function readLine() {
    return input_stdin_array[input_currentline++];
}

/////////////// ignore above this line ////////////////////

function minimumNumber(n, password) {
    // Return the minimum number of characters to make the password strong
    var numbers = "0123456789";
    var lower_case = "abcdefghijklmnopqrstuvwxyz";
    var upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    var special_characters = "!@#$%^&*()-+";
    
    var bNumber, bLower, bUpeer, bSpecial;
    
    for(var i = 0; i<n; i++){
        if(numbers.indexOf(password[i]) !== -1){
            bNumber = true;
        }
        else if(lower_case.indexOf(password[i]) !== -1){
            bLower = true;
        }
        else if(upper_case.indexOf(password[i]) !== -1){
            bUpeer = true;
        }
        else if(special_characters.indexOf(password[i]) !== -1){
            bSpecial = true;
        }
    }
    
    var ret = 0;
    if(!bNumber){
        ret++;
    }
    
    if(!bLower){
        ret++;
    }
    
    if(!bUpeer){
        ret++;
    }
    
    if(!bSpecial){
        ret++;
    }
    
    if( 6 - n > 0 && 6 - n > ret){
        ret = 6 - n;
    }
    return ret;
}

function main() {
    var n = parseInt(readLine());
    var password = readLine();
    var answer = minimumNumber(n, password);
    process.stdout.write("" + answer + "\n");

}