//1 задание
let st1 = "43"
let st2 = "4j"
let st3 = "u34"
let st4 = "35"
let st5 = "21"
var sum: Int! = nil
if Int(st1) != nil {
    if sum == nil {sum = 0}
    sum += Int(st1)!
}
if let const = Int(st2) {
    if sum == nil {sum = 0}
    sum += const
}
if let const = Int(st3) {
    if sum == nil {sum = 0}
    sum += const
}
if Int(st4) != nil {
    if sum == nil {sum = 0}
    sum += Int(st4)!
}
if let const = Int(st5) {
    if sum == nil {sum = 0}
    sum += const
}
if sum == nil {
    print("Error! The all constants is not numbers")
} else {
    print("The sum of these constants = \(sum!)")
}

//2 задание
let request: (status: Int, message: String?, error_message: String?) = (234, "Ok bro", "Nonono it's shit")

if (request.status > 200 && request.status < 300) {
    print(request.message!)
} else {
    print(request.error_message!)
}

let request0: (message: String?, error_message: String?) = (nil, "No bro")

if request0.message != nil {
    print(request0.message!)
} else if request0.error_message != nil {
    print(request0.error_message!)
} else {
    print("Error")
}

//3 задание

var student1 : (name: String?, cars_num: String?, mark: String?) = (nil, nil, nil)
var student2 : (name: String?, cars_num: String?, mark: String?) = (nil, nil, nil)
var student3 : (name: String?, cars_num: String?, mark: String?) = (nil, nil, nil)
var student4 : (name: String?, cars_num: String?, mark: String?) = (nil, nil, nil)
var student5 : (name: String?, cars_num: String?, mark: String?) = (nil, nil, nil)

student1.name = "Fred"
student2.name = "John"
student3.name = "Ann"
student4.name = "Flora"
student5.name = "Biggi"

student1.cars_num = "г353ге"
student4.cars_num = "u425wr"
student5.cars_num = "o285ww"

student1.mark = "3"
student3.mark = "4"
student4.mark = "5"
student5.mark = "2"

if let cars_n1 = student1.cars_num {
    if student1.mark != nil {
        print("Name: \(student1.name!), car's number: \(cars_n1), mark: \(student1.mark!)")
    } else {
        print("Name: \(student1.name!), car's number: \(cars_n1), no mark")
    }
} else {
    if student1.mark != nil {
        print("Name: \(student1.name!), don't have a car, mark: \(student1.mark!)")
    } else {
        print("Name: \(student1.name!), don't have a car, no mark")
    }
}
if let cars_n2 = student2.cars_num {
    if student2.mark != nil {
        print("Name: \(student2.name!), car's number: \(cars_n2), mark: \(student2.mark!)")
    } else {
        print("Name: \(student2.name!), car's number: \(cars_n2), no mark")
    }
} else {
    if student2.mark != nil {
        print("Name: \(student2.name!), don't have a car, mark: \(student2.mark!)")
    } else {
        print("Name: \(student2.name!), don't have a car, no mark")
    }
}
if let cars_n3 = student3.cars_num {
    if student3.mark != nil {
        print("Name: \(student3.name!), car's number: \(cars_n3), mark: \(student3.mark!)")
    } else {
        print("Name: \(student3.name!), car's number: \(cars_n3), no mark")
    }
} else {
    if student3.mark != nil {
        print("Name: \(student3.name!), don't have a car, mark: \(student3.mark!)")
    } else {
        print("Name: \(student3.name!), don't have a car, no mark")
    }
}
if let cars_n4 = student4.cars_num {
    if student4.mark != nil {
        print("Name: \(student4.name!), car's number: \(cars_n4), mark: \(student4.mark!)")
    } else {
        print("Name: \(student4.name!), car's number: \(cars_n4), no mark")
    }
} else {
    if student4.mark != nil {
        print("Name: \(student4.name!), don't have a car, mark: \(student4.mark!)")
    } else {
        print("Name: \(student4.name!), don't have a car, no mark")
    }
}
if let cars_n5 = student5.cars_num {
    if student5.mark != nil {
        print("Name: \(student5.name!), car's number: \(cars_n5), mark: \(student5.mark!)")
    } else {
        print("Name: \(student5.name!), car's number: \(cars_n5), no mark")
    }
} else {
    if student5.mark != nil {
        print("Name: \(student5.name!), don't have a car, mark: \(student5.mark!)")
    } else {
        print("Name: \(student5.name!), don't have a car, no mark")
    }
}