Find Duplicate in Range 0 and n-1

#include <stdio.h>

int find_duplicate(int arr[], int n) {
    // Your logic here
    int k,m;
    for(k=0;k<n;k++){
        for(m=k+1;m<n;m++){
            if(arr[k]==arr[m]) return arr[k];
        }

    }
}

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;
}