exercise 11.1 Cycle for (Students marks)

import Foundation
import Glibc
 
var students : [String:[String:UInt]] = ["Kirill":["3th of november": 1, "21st of september": 4], 
"Dasha":["13th of september": 4, "3th of november": 3], 
"Nikita": ["24th of october": 2, "13th of september": 3]]
var studentsAvagrages : Float = 0
for (name, dateAndMark) in students {
    var studentAvarage : Float = 0
    var sumOfAllMarks : UInt = 0
    for (_, mark) in dateAndMark{
        sumOfAllMarks += mark
    }
    studentAvarage = Float(sumOfAllMarks) / Float(dateAndMark.count)
    print("Avarage mark for student \(name) is \(studentAvarage)")
    studentsAvagrages += studentAvarage
}
studentsAvagrages = studentsAvagrages / Float(students.count)
print("Avarage mark of all students is \(studentsAvagrages)")