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.
For example, the array of mineral composition strings . The minerals and appear in each composite, so there are gemstones.
Complete the gemstones function in the editor below. It should return an integer representing the number of gemstones found in the list of rocks.
gemstones has the following parameter(s):
arr: an array of strings
The first line consists of an integer , the size of .
Each of the next lines contains a string where each letter represents an occurence of a mineral in the current rock.
| arr[i] |
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 because they are the only types that occur in every rock.