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


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);
		TaskC solver = new TaskC();
		solver.solve(1, in, out);
		out.close();
	}

	static class TaskC {
		public int mod = 1000000007;

		public void solve(int testNumber, InputReader in, OutputWriter out) {
			int[] a = in.readIntArray(3);
			Arrays.sort(a);
			int ans = a[2] - a[1];
			a[0] += ans;
			if ((a[2] - a[0]) % 2 != 0) {
				ans++;
				a[2]++;
			}
			ans += (a[2] - a[0]) / 2;
			out.println(ans);
		}

		static class Query {
			public int l;
			public int x;
			public int idx;

			public Query(int l, int x, int idx) {
				this.l = l;
				this.x = x;
				this.idx = idx;
			}

		}

	}

	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 print(int[] array) {
			for (int i = 0; i < array.length; i++) {
				if (i != 0) {
					writer.print(' ');
				}
				writer.print(array[i]);
			}
		}

		public void println(int[] array) {
			print(array);
			writer.println();
		}

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

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

	}

	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 Utils {
		public static int[] genPower(int base, int len, int mod) {
			int[] ret = new int[len];
			ret[0] = 1;
			for (int i = 1; i < len; i++)
				ret[i] = (int) (1L * ret[i - 1] * base % mod);
			return ret;
		}

	}

	static class Basis {
		public int size;
		public long[] basis;

		public Basis() {
			basis = new long[100];
			size = 0;
		}

		public boolean add(long x) {
			for (int i = size - 1; i >= 0; i--) {
				x = Math.min(x, x ^ basis[i]);
			}
			if (x == 0)
				return false;
			basis[size++] = x;
			for (int i = size - 2; i >= 0; i--) {
				if (basis[i] > basis[i + 1]) {
					long t = basis[i + 1];
					basis[i + 1] = basis[i];
					basis[i] = t;
				}
			}
			return true;
		}

		public boolean test(long x) {
			for (int i = size - 1; i >= 0; i--) {
				x = Math.min(x, x ^ basis[i]);
			}
			return x == 0;
		}

	}
}


Measured memory_bytes: 21460