n910f 5.1.1 root help

hi how to root n910f im having write cert problem log below anyone can help

Checking certificate file… OK
KEY ID: 0772
Waiting ADB device… OK
Reading phone info…
Model: SM-N910F
Android version: 5.1.1
Product code: SM-N910FZWEBTU
Phone version: N910FXXU1COI3
PDA version: N910FXXU1COI3
CSC version: N910FBTU1COI1
CSC country code: UK & IRE
CSC sales code: BTU
HW version: MP 0.900
Phone S/N: RF8G21CFFPR
Modem board: MDM9235
RF cal date: 2015.02.14
Initialization AT RIL… OK
Bypass MSL… OK
Checking for compatible phone and cert… OK
Phone KEY ID: 0772
Writing CERT… error (0)

Done with Samsung Tool PRO v.24.1