find duplicate array with c

array_find.cpp

#include  <stdio.h>

int main()
{
    int input;
    int arr[] = {2,3,6,1,7,9,7,3,5,7,2,5,8,5};
    int output = 0;

    printf("\n Please Enter Number of elements in an array  :   ");
	  scanf("%d", &input);


    int arr_size = (int)sizeof(arr)/sizeof(int);
    for(int i = 0; i < arr_size; i++)
    {
        if (arr[i] == input) {
            output++;
        }
    }

    printf ("Total array %d is %d \n", input, output);
}