How to extend C drive in windows 7 without formatting it?

i have wondows 7 ulmilate unfortunalty i left C drive only 9 gb at installing time.. now i am undale to install any software because there is no extra space in drive C.. i just want to extend this drive but i didnt find any option in disk management,.only it has shrink volume option no extend option so what to do... show more i have wondows 7 ulmilate unfortunalty i left C drive only 9 gb at installing time.. now i am undale to install any software because there is no extra space in drive C.. i just want to extend this drive but i didnt find any option in disk management,.only it has shrink volume option no extend option so what to do now.. i dont wanna format drive or uninstall windows because i have to backup all data which takes so much time..so suggest me some quick and better option.. thanks to read.. thanks in advance.. tc
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