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 doDodania = 4;
    

    function czyZawiera(password, n, zbior) {
        for (var i = 0; i < n; i++){
            for (var j = 0; j < zbior.length; j++){
                //console.log("password[i]" + password[i] + " zbior[j]" +  zbior[j])
                if (password[i] == zbior[j]) {
                    doDodania--;
                    return;
                }
            }
        }
    }
    czyZawiera(password, n, numbers); 
    //console.log(doDodania);
    czyZawiera(password, n, lower_case);
    //console.log(doDodania);
    czyZawiera(password, n, upper_case);
    //console.log(doDodania);
    czyZawiera(password, n, special_characters);
    //console.log(doDodania);
    
    if (n + doDodania < 6) { doDodania = 6 - n}
    return doDodania;
}

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

}