Find Duplicate in Range 0 and n-1

#include <stdio.h>

int find_duplicate(int arr[], int n) {
    // Your logic here
    // Compare each element with all elements after it
    for (int i = 0; i < n - 1; i++) 
    {
        for (int j = i + 1; j < n; j++) 
        {
            if (arr[i] == arr[j])   // Only reads arr[i] and arr[j]
            {
                return arr[i];      // returns the duplicate value
            }
        }
    }
    
    return -1;
}

int main() {
    int n;
    scanf("%d", &n);

    int arr[100];
    for (int i = 0; i < n; i++) scanf("%d", &arr[i]);

    int result = find_duplicate(arr, n);
    printf("%d", result);
    return 0;
}