AOJ 2792 SNS

Solved Users (link to submissions)
aizu_e
arrows
autumn_eel
bal4u
c7c7
dohatsu
dyuma
ei1333
haji149
kmcyuma
Lapinpon
leafmoon
masa002
namonakiaccount
naoto172
rabelice
somen31
T1610
tnakao
tossy
vvataarne
yana87
Yazaten
yebityon