def is_bipartite(adj):
    color = [-1] * len(adj)
    for start in range(len(adj)):
        if color[start] != -1:
            continue
        color[start] = 0
        stack = [start]
        while stack:
            u = stack.pop()
            for v in adj[u]:
                if color[v] == -1:
                    color[v] = 1 - color[u]
                    stack.append(v)
                elif color[v] == color[u]:
                    return False
    return True