from typing import List


class IntCode:
    def __init__(self, memory: List[int], mem_size: int = 0):
        self.instr_ptr = 0
        self.halted = False
        self.memory = memory
        if len(self.memory) < mem_size:
            self.memory.extend([0] * (mem_size - len(self.memory)))

    def run(self):
        while not self.halted:
            instr = self.memory[self.instr_ptr]

            if instr == 1:
                address1 = self.memory[self.instr_ptr + 1]
                address2 = self.memory[self.instr_ptr + 2]
                address3 = self.memory[self.instr_ptr + 3]
                self.memory[address3] = self.memory[address1] + self.memory[address2]
                self.instr_ptr += 4
            elif instr == 2:
                address1 = self.memory[self.instr_ptr + 1]
                address2 = self.memory[self.instr_ptr + 2]
                address3 = self.memory[self.instr_ptr + 3]
                self.memory[address3] = self.memory[address1] * self.memory[address2]
                self.instr_ptr += 4
            elif instr == 99:
                self.halted = True
            else:
                raise ValueError("Invalid instruction encountered at pos %d: %d" % (self.instr_ptr, instr))