email1 = 'mr.reilly@gmail.com'
email2 = 'john55@yahoo.com'
email3 = 'elgringo@atlas.sk'

posa1 = email1.index('@')
posa2 = email2.index('@')
posa3 = email3.index('@')

print(email1[:posa1])
print(email2[:posa2])
print(email3[:posa3])
