代码大概就是酱紫的：

#include <bits/stdc++.h>
using namespace std;
freopen ("range.in", "r", stdin);
freopen ("range.out", "w", stdout);
int n, k, corpse [10009];
int main () {
	scanf ("%d %d", &n, &k);
	for (int i = 0; i < n; i ++) {
    	scanf ("%d", corpse [i]);
    	corpse [i] = abs (corpse [i]);
    }
	sort (corpse, corpse + n);
	printf ("%d", corpse [k]);
	return 0;
}

求助！！！