// Problem: 257_A. Sockets
// Time complexity: nlogn
import java.util.Arrays;
import java.util.InputMismatchException;
import java.io.*;

/**
 * Generated by Contest helper plug-in
 * Actual solution is at the bottom
 */
public class Main {
    public static void main(String[] args) {
        InputReader in = new StreamInputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);
        run(in, out);
    }

    public static void run(InputReader in, PrintWriter out) {
        Solver solver = new TaskB();
        solver.solve(1, in, out);
        Exit.exit(in, out);
    }
}

abstract class InputReader {
    private boolean finished = false;

    public abstract int read();

    public int readInt() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        int res = 0;
        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res *= 10;
            res += c - '0';
            c = read();
        } while (!isSpaceChar(c));
        return res * sgn;
    }

    public String readString() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        StringBuffer res = new StringBuffer();
        do {
            res.appendCodePoint(c);
            c = read();
        } while (!isSpaceChar(c));
        return res.toString();
    }

    private boolean isSpaceChar(int c) {
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    public void setFinished(boolean finished) {
        this.finished = finished;
    }

    public abstract void close();
}

class StreamInputReader extends InputReader {
    private InputStream stream;
    private byte[] buf = new byte[1024];
    private int curChar, numChars;

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

    public int read() {
        if (numChars == -1)
            throw new InputMismatchException();
        if (curChar >= numChars) {
            curChar = 0;
            try {
                numChars = stream.read(buf);
            } catch (IOException e) {
                throw new InputMismatchException();
            }
            if (numChars <= 0)
                return -1;
        }
        return buf[curChar++];
    }

    public void close() {
        try {
            stream.close();
        } catch (IOException ignored) {
        }
    }
}

class Exit {
    private Exit() {
    }

    public static void exit(InputReader in, PrintWriter out) {
        in.setFinished(true);
        in.close();
        out.close();
    }
}

interface Solver {
    public void solve(int testNumber, InputReader in, PrintWriter out);
}

class TaskB implements Solver 
{
    public void solve(int testNumber, InputReader in, PrintWriter out) 
    {
        int n = in.readInt();
        int m = in.readInt();
        int k = in.readInt();
        int[] a = new int[n];
        for(int i=0;i<n;i++) a[i] = in.readInt();
        Arrays.sort(a);
        if(k>=m)
        {
            out.println(0);
        }
        else
        {
            for(int i=n-1;i>=0;i--)
            {
                k += (a[i]-1);
                if(k>=m) 
                {
                    out.println(n-i);
                    return;
                }
            }
            if(k<m) out.println(-1);
        }
    }
}