Answer is:
First fill 5 litre and pour it into 7 Lit.
Then again fill 5 litre and pour to 7 lit.
now 3 liter left in 5 liter container!
emply 7 litre and pour 3 litre in it.
again fill 5 litre and pour in 7 liter.
now 7 litre is full and 1 liter left in 5 liter container.
empty 7 litre and pour 1 liter which is left in 5 liter container.
now 1 liter is already in 7 liter container, now fill 5 liter and pour into 7 liter container.
now it is 6 liter in 7 liter container.....
problem is sloved.
Manoj