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

buf = sys.stdin.buffer
input = sys.stdin.buffer.readline


def main():
    H, W = map(int, input().split())
    A = (np.frombuffer(buf.read(), dtype='S1')[::2] == b'1').reshape((H, W))
    F = np.arange(H * W).reshape((H, W))
    ct_0 = np.count_nonzero(~A)

    HC = A[1:] & A[:-1]
    ZW = np.zeros(W, dtype=bool).reshape(1, W)
    frm1 = F[np.concatenate([ZW, HC], 0)]
    to1 = F[np.concatenate([HC, ZW], 0)]
    del HC, ZW

    WC = A[:, 1:] & A[:, :-1]
    ZH = np.zeros(H, dtype=bool).reshape(H, 1)
    frm2 = F[np.concatenate([ZH, WC], 1)]
    to2 = F[np.concatenate([WC, ZH], 1)]
    del WC, ZH
    del A, F

    frm = np.hstack((frm1, frm2))
    to = np.hstack((to1, to2))
    L = len(frm)
    matr = csr_matrix(([1] * L, (frm, to)), shape=(H * W, H * W))
    p = connected_components(matr, return_labels=False)
    ans = p - ct_0
    return ans


print(main())