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 ////////////////////

const numbers = "0123456789"
const lowerCase = "abcdefghijklmnopqrstuvwxyz"
const upperCase = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
const specialCharacters = "!@#$%^&*()-+"

function minimumNumber(n, password) {
    let counter = [0, 0, 0, 0];
    let needMore = 0;
    
    if (password.length < 6) {
        needMore = 6 - password.length;
    }
    
    password.split('').forEach(char => {
        if (numbers.indexOf(char) !== -1) {
            counter[0] = 1; 
        }
        
        if (lowerCase.indexOf(char) !== -1) {
            counter[1] = 1; 
        }
        
        if (upperCase.indexOf(char) !== -1) {
            counter[2] = 1; 
        }
        
        if (specialCharacters.indexOf(char) !== -1) {
            counter[3] = 1; 
        }
    });
    
    const result = counter.filter(a => !a).length;
    
    if (needMore > result) {
        return needMore;
    } else {
        return result;
    }
}

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

}