class Friends:
    def __init__(self, connections):
        self.imiona = list(connections)
        
    def names(self):    #getter
        list1, list2 = zip(*self.imiona)
        list3 = set(list1 + list2)
        return(list3)      
    
    def add(self, connection):  #setter
        self.connection = connection    #set
        self.imiona.sort()               #lista
        if self.connection in self.imiona:
            return(False)
        else:
            self.imiona.append(self.connection)
            return(True)
        
    def remove(self, connection):   #deleter
        self.connection = connection    #set

        try:
            self.imiona.remove(self.connection)
            return(True)
        except ValueError: return(False)
        
    def connected(self, name):
        try:
            temp=[]
            self.name = name
            for i in self.imiona:
                if self.name in i:
                    temp.append(i.difference({self.name}))
            a=str(temp).strip('[').strip(']').replace('\'','\"')
            return(a)

        except ValueError:
            return("")