//1 задание
var journal =  ["Alex B" : 4, "Johnny C" : 3, "Gavrila H" : 5, "Tosya M" : 3, "Tur" : 4]
journal["Johnny C"] = 5
journal["Tosya M"] = 4
journal["Fred G"] = 3
journal["Kira T"] = 5
journal["Alex B"] = nil
journal["Tur"] = nil
var total = Int()
var avarage = Double()
for value in journal.values {
    total += value
}
avarage = Double(total) / Double(journal.count)
print("The total score of group: \(total), the avarage score: \(avarage)\n")

//2 задание
let moths = ["Jan" : 31, "Feb" : 28, "Mar" : 31, "Apr" : 30, "May" : 31, "Jun" : 30, "Jul" : 31, "Aug" : 31, "Sep" : 30, "Oct" : 31, "Nov" : 31, "Dec" : 31]
for (key, value) in moths {
    print("Moth : \(key) - days : \(value)")
}
print("\n")
for moth in moths.keys {
    print("Moth : \(moth) - days : \(moths[moth]!)")
}
var chess = [String : Bool]()
var i = 1
for letter in "ABCDEFGH" {
    for num in "12345678" {
        let num = String(num)
        let letter = String(letter)
        if (i + Int(num)!) % 2 == 0 {
            chess[letter + num] = false
        } else {
            chess[letter + num] = true
        }
    }
}
print(chess)