import sys
import numpy as np
from scipy.sparse.csgraph import connected_components
from scipy.sparse import csr_matrix

input = sys.stdin.buffer.readline


def main():
    H, W = map(int, input().split())
    A = np.array([tuple(map(int, input().split())) for _ in range(H)], dtype=bool)
    F = np.arange(H * W).reshape((H, W))

    HC = A[1:] & A[:-1]
    WC = A[:, 1:] & A[:, :-1]
    ZW = np.zeros(W, dtype=bool).reshape(1, W)
    ZH = np.zeros(H, dtype=bool).reshape(H, 1)
    frm = np.hstack((F[np.concatenate([ZW, HC], 0)],
                     F[np.concatenate([ZH, WC], 1)]))
    to = np.hstack((F[np.concatenate([HC, ZW], 0)],
                    F[np.concatenate([WC, ZH], 1)]))
    L = len(frm)
    matr = csr_matrix(([1] * L, (frm, to)), shape=(H * W, H * W))
    p = connected_components(matr, return_labels=False)
    ans = p - np.count_nonzero(~A)
    return ans


print(main())