Help me in solving CFRTEST problem

My issue

sol.cpp: In function ‘int main()’:
sol.cpp:16:13: error: ‘sort’ was not declared in this scope; did you mean ‘short’?
16 | sort(arr,arr+n);
| ^~~~
| short

My code

#include <iostream>
using namespace std;

int main() {
	// your code goes here
	int t;
	cin>>t;
	while(t--){
	    int n;
	    cin>>n;
	    int count=0;
	    int arr[n];
	    for(int i=0;i<n;i++){
	        cin>>arr[i];
	    }
	    sort(arr,arr+n);
	    for(int i=0;i<n;i++){
	        if(arr[i]==arr[i+1])
	        count++;
	    }
	    int result;
	    result=n-count;
	    cout<<result<<endl;
	}
	return 0;
}

Learning course: Arrays, Strings & Sorting
Problem Link: Practice Problem in - CodeChef

add #include<bits/stdc++.h> header file then check again…