Data search question in C language binary search.

#include<stdio.h>
#include<stdlib.h>

int idxsearch(int ar[], int first, int last, int target) {
    int mid = (first + last) / 2;
    if (first > last)
        return -1;
    else {
        if (ar[mid] == target)
            return mid;
        else {
            if (ar[mid] > target) {
                last = mid - 1;
                idxsearch(ar, first, last, target);
            }
            else {
                first = mid + 1;
                idxsearch(ar, first, last, target);
            }
        }
    }
}
int main() {
    scanf_s(" %d", &num);
    int *inorder = malloc(sizeof(int)*num);
    int *levelorder = malloc(sizeof(int)*num);

    for (int i = 0; i < num; i++)
        scanf_s(" %d", &inorder[i],sizeof(int));
    for (int j = 0; j < num; j++)
        scanf_s(" %d", &levelorder[j],sizeof(int));
    printf("\n");

    printf(" %d\n", idxsearch(inorder, 0, num-1, 3));
    printf(" %d\n", idxsearch(levelorder, 0, num-1, 1));

    //printsol();
    free(levelorder);
    free(inorder);
}