Given a string **S** consisting of lowercase English alphabets, the task is to find the number of unique characters present in the string.

**Examples:**

Input:S = “geeksforgeeks”Output:7Explanation:The given string “geeksforgeeks” contains 6 unique characters {‘g’, ‘e’, ‘k’, ‘s’, ‘f’, ‘o’, ‘r’}.

Input:S = “madam”Output:3

**Approach:** The idea to solve the given problem is to initialize a Set() in python to store all distinct characters of the given string and then, print the size of the set as the required answer.

Below is the implementation of the above approach:

## Python3

`# Python program for the above approach` `# Function to count the number of distinct` `# characters present in the string str` `def` `countDis(` `str` `):` ` ` `# Stores all distinct characters` ` ` `s ` `=` `set` `(` `str` `)` ` ` `# Return the size of the set` ` ` `return` `len` `(s)` `# Driver Code` `if` `__name__ ` `=` `=` `"__main__"` `:` ` ` `# Given string S` ` ` `S ` `=` `"geeksforgeeks"` ` ` `print` `(countDis(S))` |

**Output:**

7

**Time Complexity:** O(N)**Auxiliary Space:** O(1)

#### Method 2: Using **Counter **function:

Count the frequencies of all elements using Counter function and number of keys of this frequency dictionary gives the result.

Below is the implementation:

## Python3

`# Python program for the above approach` `from` `collections ` `import` `Counter` `# Function to count the number of distinct` `# characters present in the string str` `def` `countDis(` `str` `):` ` ` `# Stores all frquencies` ` ` `freq ` `=` `Counter(` `str` `)` ` ` `# Return the size of the freq dictionary` ` ` `return` `len` `(freq)` `# Driver Code` `if` `__name__ ` `=` `=` `"__main__"` `:` ` ` `# Given string S` ` ` `S ` `=` `"geeksforgeeks"` ` ` `print` `(countDis(S))` ` ` `# This code is contributed by vikkycirus` |

**Output:**

7

**Time Complexity: **O(N)

**Auxiliary Space: **O(N)

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