Let $A, B$ and $C$ be three sets such that:

- $|A|=100,|B|=50$ and $|C|=48$,

- the number of elements belonging to exactly one of the three sets is equal to twice the number of elements belonging to exactly two of the sets,
- the number of elements belonging to exactly one of the three sets is equal to three times the number of elements belonging to all the sets.

How many elements belong to all the sets?