import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.io.BufferedWriter;
import java.io.Writer;
import java.io.OutputStreamWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 *
 * @author lewin
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        OutputWriter out = new OutputWriter(outputStream);
        TaskE solver = new TaskE();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskE {
        public int get(int[] arr, int k, int sm, int big) {
            int good = 0, tot = 0;
            int ans = 0;
            for (int j = 0; j < arr.length; j++) {
                if (arr[j] < sm) {
                    ans += Math.max(0, Math.min(tot - k + 1, good));
                    good = 0;
                    tot = 0;
                } else {
                    tot++;
                    if (arr[j] <= big) good++;
                }
            }
            ans += Math.max(0, Math.min(tot - k + 1, good));
            return ans;
        }

        public void solve(int testNumber, InputReader in, OutputWriter out) {
            int n = in.nextInt(), k = in.nextInt(), q = in.nextInt();
            int[] arr = in.readIntArray(n);
            int[] brr = Arrays.copyOf(arr, n);
            AUtils.sort(brr);

            int ret = brr[q - 1] - brr[0];
            for (int small = 0; small < brr.length; small++) {
                int lo = small, hi = brr.length;
                while (lo < hi) {
                    int mid = (lo + hi) / 2;
                    if (get(arr, k, brr[small], brr[mid]) >= q) hi = mid;
                    else lo = mid + 1;
                }
                if (lo < brr.length) {
                    ret = Math.min(ret, brr[lo] - brr[small]);
                }
            }
            out.println(ret);
        }

    }

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1 << 16];
        private int curChar;
        private int numChars;

        public InputReader(InputStream stream) {
            this.stream = stream;
        }

        public int[] readIntArray(int tokens) {
            int[] ret = new int[tokens];
            for (int i = 0; i < tokens; i++) {
                ret[i] = nextInt();
            }
            return ret;
        }

        public int read() {
            if (this.numChars == -1) {
                throw new InputMismatchException();
            } else {
                if (this.curChar >= this.numChars) {
                    this.curChar = 0;

                    try {
                        this.numChars = this.stream.read(this.buf);
                    } catch (IOException var2) {
                        throw new InputMismatchException();
                    }

                    if (this.numChars <= 0) {
                        return -1;
                    }
                }

                return this.buf[this.curChar++];
            }
        }

        public int nextInt() {
            int c;
            for (c = this.read(); isSpaceChar(c); c = this.read()) {
                ;
            }

            byte sgn = 1;
            if (c == 45) {
                sgn = -1;
                c = this.read();
            }

            int res = 0;

            while (c >= 48 && c <= 57) {
                res *= 10;
                res += c - 48;
                c = this.read();
                if (isSpaceChar(c)) {
                    return res * sgn;
                }
            }

            throw new InputMismatchException();
        }

        public static boolean isSpaceChar(int c) {
            return c == 32 || c == 10 || c == 13 || c == 9 || c == -1;
        }

    }

    static class AUtils {
        public static void sort(int[] arr) {
            for (int i = 1; i < arr.length; i++) {
                int j = (int) (Math.random() * (i + 1));
                if (i != j) {
                    int t = arr[i];
                    arr[i] = arr[j];
                    arr[j] = t;
                }
            }
            Arrays.sort(arr);
        }

    }

    static class OutputWriter {
        private final PrintWriter writer;

        public OutputWriter(OutputStream outputStream) {
            writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
        }

        public OutputWriter(Writer writer) {
            this.writer = new PrintWriter(writer);
        }

        public void close() {
            writer.close();
        }

        public void println(int i) {
            writer.println(i);
        }

    }
}

