class Stat:
    def __init__(self, name, values, index=0):
        self.name = name
        self.values = values
        self.index = index
    def get_value(self):
        return self.values[self.index]
    def set_index(self, i):
        self.index = i
        if self.index < 0:
            self.index = (self.index+len(self.values))%len(self.values)
        if self.index >= len(self.values):
            self.index = self.index%len(self.values)
    def change_index(self, delta):
        new_index = self.index+delta
        self.set_index(new_index)