#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <math.h>
#include <queue>
using namespace std;

const int MAXN = 2000 + 10;
int N, M, Q;
int A[MAXN];
int ans = 999999999;

int main() {
	register int i, j;
	scanf( "%d%d%d", &N, &M, &Q );
	for( i = 1; i <= N; ++i )
		scanf( "%d", A + i );
	for( i = 1; i <= N - M + 1; ++i ) {
		int x = 0, y = 99999999;
		for( j = 1; j <= M; ++j )
			x = max(x, A[i + j - 1]), y = min(y, A[i + j - 1]);
		ans = min( ans, x - y );
	}
	printf( "%d\n", ans );
	return 0;
}