#!/usr/bin/perl -wn
print if /^(f(o[^o]|[^o])|[^f])*$/;
IyEvdXNyL2Jpbi9wZXJsIC13bgpwcmludCBpZiAvXihmKG9bXm9dfFteb10pfFteZl0pKiQvOwo=
ZiwgZm8gb3IgYmFyZgpmCmZvCmJhcmYKZm9vCidmb28nCmFiZGZvb2RlCmFiZGZvZGUKYWJkZmRlCmFiY2RlCmYKCiAKZm8KZm9vCmZvb28Kb2Zvb2EKb2ZvCm9mb28=
f, fo or barf
f
fo
barf
foo
'foo'
abdfoode
abdfode
abdfde
abcde
f
fo
foo
fooo
ofooa
ofo
ofoo