2026-03-15 16:53:42 +0300 MSK

class Fancy:

    def __init__(self):
        self.mod = 10**9 + 7
        self.v = list()
        self.a = 1
        self.b = 0

    # fast exponentiation
    def quickmul(self, x: int, y: int) -> int:
        return pow(x, y, self.mod)

    # multiplicative inverse
    def inv(self, x: int) -> int:
        return self.quickmul(x, self.mod - 2)

    def append(self, val: int) -> None:
        self.v.append((val - self.b) * self.inv(self.a) % self.mod)

    def addAll(self, inc: int) -> None:
        self.b = (self.b + inc) % self.mod

    def multAll(self, m: int) -> None:
        self.a = self.a * m % self.mod
        self.b = self.b * m % self.mod

    def getIndex(self, idx: int) -> int:
        if idx >= len(self.v):
            return -1
        return (self.a * self.v[idx] + self.b) % self.mod