John has collected various rocks. Each rock has various minerals embeded in it. Each type of mineral is designated by a lowercase letter in the range . There may be multiple occurrences of a mineral in a rock. A mineral is called a gemstone if it occurs at least once in each of the rocks in John's collection.
Given a list of minerals embedded in each of John's rocks, display the number of types of gemstones he has in his collection.
The first line consists of an integer , the number of rocks.
Each of the next lines contains a string where each letter represents an occurence of a mineral in the current rock.
length of each composition
Each composition consists of only lower-case Latin letters ('a'-'z').
Print the number of types of gemstones in John's collection. If there are none, print .
Only and are gemstones. They are the only types that occur in every rock.