def checkio(line):
    'Calculate amount of words which contain exactly two "o" letters'
    result = 0
    alist = line.split()

    for words in alist:
        if 'oo' in words:
            result += 1

    return result

if __name__ == '__main__':
    assert checkio('voodo google soon color job') == 3, 'First'
    print('All ok')


#By ephexeve.blogspot.com