### PROBLEM LINK:

**Author:** avi224

**Editorialist:** avi224

### DIFFICULTY:

CAKEWALK.

### PREREQUISITES:

STL

### PROBLEM:

Print the sum of all numbers in an array occurring exactly K times. If there is no such number, print -1.

### EXPLANATION:

This can be implemented by using a map or unordered map in C++. Just take the sum of numbers whose frequency is K, considering each number only once.