import re

def make_3sg_form(verb):
    es = ('o','ch','s','sh','x','z')

    if verb.endswith('y'):
        return re.sub('y$', 'ies', verb)
    elif verb.endswith(es):
        return verb + 'es'
    else:
        return verb + 's'

if __name__ == "__main__":
    print(make_3sg_form('try'))
    print(make_3sg_form('brush'))
    print(make_3sg_form('run'))
    print(make_3sg_form('fix'))