Common Minerals

You are given T rock samples represented as strings of lowercase letters, where each letter corresponds to a mineral found in that rock. Your task is to find the number of minerals that are common to all rock samples. In other words, if we define (S_i) as the set of minerals in the (i^{th}) rock sample, you must compute (|\bigcap_{i=1}^{T} S_i|).

For example, if the input is:
3
abcdde
baccd
eeabg
then the common minerals are 'a' and 'b', and the output should be 2.

inputFormat

The input is provided via standard input and consists of multiple lines. The first line contains a single integer (T) ((1 \le T \le 10^4)), the number of rock samples. The following (T) lines each contain a non-empty string composed only of lowercase letters, representing a rock sample.

outputFormat

Output a single integer representing the number of minerals (letters) that appear in every rock sample.## sample

3
abcdde
baccd
eeabg

2