accounts = []
class Account:
    def __init__(s):
        global accounts
        s.debits = []
        s.credits = []
        accounts += [s]
        
    def add_to_debits(self,value):
        self.debits += [value]
    def add_to_credits(self,value):
        self.credits += [value]
    def total_value(self):
        total =0 
        for val in self.debits:
            total-=val
        for val in self.credits:
            total+=val
        return total