fsck error

[nirp1995]

I want to know how to solve this error? help me out!!

INPUT fsck -n /dev/nandb"
OUTPUT
fsck from util-linux 2.25.2
e2fsck 1.42.12 (29-Aug-2014)
Warning! /dev/nandb is mounted.
/dev/nandb contains a file system with errors, check forced.
Pass 1: Checking inodes, blocks, and sizes
Deleted inode 389 has zero dtime. Fix? no
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
Block bitmap differences: -(34036--34059) -(1097199--1097472) -(1119106--1119161) -(1608640--1608649) -(1616520--1616569) -(1644614--1644615) -(1644726--1644727) -(1644784--1644785) -(1645185--1645186) -(1646267--1646268) -(1646403--1646412) -(1655093--1655094) -(1655655--1655664) -(1655805--1655806)
Fix? no
Free blocks count wrong for group #49 (802, counted=809).
Fix? no
/dev/nandb: ********** WARNING: Filesystem still has errors **********
/dev/nandb: 62693/486720 files (0.2% non-contiguous), 444968/1943536 blocks