Unique number 3

[Learning_bunny (Piyush Gupta)]

i have done 1 and 2 but cant get how to do this one

[aman212yadav (Aman Yadav)]

@Learning_bunny
hello piyush,
pls refer this article -> https://www.geeksforgeeks.org/find-the-element-that-appears-once/