import heapq


def dijkstra(graph, start):
    dist = {v: float("inf") for v in graph}
    dist[start] = 0
    pq = [(0, start)]
    while pq:
        d, v = heapq.heappop(pq)
        if d > dist[v]:
            continue
        for u, w in graph[v]:
            if dist[v] + w < dist[u]:
                dist[u] = dist[v] + w
                heapq.heappush(pq, (dist[u], u))
    return dist


if __name__ == "__main__":
    graph = {
        "Невский": [("Лиговский", 5), ("Гороховая", 3)],
        "Лиговский": [("Московский", 7)],
        "Гороховая": [("Московский", 4)],
        "Московский": [],
    }
    print(dijkstra(graph, "Невский"))