from heapq import heappush, heappop

class Element:
    def __init__(self, key, string):
        self.key = key
        self.data = string

class MinPriorityQueue:
    def __init__(self):
        self.heap = []

    def is_empty(self):
        if not self.heap:
            return True
        return False

    def push(self, item):
        heappush(self.heap, (item.key, item.data))

    def pop(self):
        return heappop(self.heap)

    def min(self):
        return self.heap[0]