How do i sort these values using Bash Script in Linux?

[matharoo]

-53 45

-54 43

-55 42

-56 41

-57 40

-59 37

-61 35

-61 36

-62 34

-64 33

-65 31

-65 32

-67 30

-68 29

-69 28

-72 25

-73 23

-73 24

-74 22

-76 20

-76 22

-78 20

-79 18

-80 17

-81 16

In the above you will see that at -61 occurs twice and so do some other values. I want to just create a new file without any duplicates. So the new file should have either -61 35 or -61 36 ...

how do i do that?! I tried using sort using uniq but that didn't work.. Please help!?

[ravi89]

sort -t" " -nuk 1 filename.txt