def start():
    n = int(input())
    mtr = [[0 for i in range(n)] for j in range(n)]
    for i in range(n):
        ss = input().split(' ')
        row = list(map(int, ss))
        for j in range(n):
            tmp = row[j]
            mtr[i][j] = tmp
            mtr[j][i] = tmp
    chk = [0 for i in range(n)]
    num_est = 0
    while True:
        flg = True
        for i in range(n):
            if chk[i] == 0:
                flg = False
                num_est = num_est + 1
                chk[i] = 1
                dfs(i, mtr, chk)
                break
        if not flg:
            return num_est


def dfs(v, mtr, chk):
    len_i = len(mtr)
    for i in range(len_i):
        if chk[i] == 0 and mtr[i][v] != 0:
            chk[i] = 1
            dfs(i, mtr, chk)


if __name__ == '__main__':
    ans = start()
    print(ans)