import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.util.NoSuchElementException;

public class Main {
    
    static PrintWriter out;
    static InputReader ir;
    
    static void solve() {
        int[] a = ir.nextIntArray(3);
        int mi = (int) 1e9;
        for (int i = -50; i <= 100; i++) {
            int c = 0;
            for (int j = 0; j < 3; j++) {
                if (a[j] >= i)
                    c += a[j] - i;
                else
                    c += (i - a[j]) % 2 == 0 ? (i - a[j]) / 2 : (i - a[j] + 1) / 2 + 1;
            }
            mi = Math.min(mi, c);
        }
        out.println(mi);
    }
    
    static void write(char[][] map) {
        for (int i = 0; i < map.length; i++) {
            for (int j = 0; j < map[i].length; j++)
                out.print(Character.toString(map[i][j]));
            out.println();
        }
    }
    
    public static void main(String[] args) throws Exception {
        ir = new InputReader(System.in);
        out = new PrintWriter(System.out);
        solve();
        out.flush();
    }
    
    static class InputReader {
        
        private InputStream in;
        private byte[] buffer = new byte[1024];
        private int curbuf;
        private int lenbuf;
        
        public InputReader(InputStream in) {
            this.in = in;
            this.curbuf = this.lenbuf = 0;
        }
        
        public boolean hasNextByte() {
            if (curbuf >= lenbuf) {
                curbuf = 0;
                try {
                    lenbuf = in.read(buffer);
                } catch (IOException e) {
                    throw new InputMismatchException();
                }
                if (lenbuf <= 0)
                    return false;
            }
            return true;
        }
        
        private int readByte() {
            if (hasNextByte())
                return buffer[curbuf++];
            else
                return -1;
        }
        
        private boolean isSpaceChar(int c) {
            return !(c >= 33 && c <= 126);
        }
        
        private void skip() {
            while (hasNextByte() && isSpaceChar(buffer[curbuf]))
                curbuf++;
        }
        
        public boolean hasNext() {
            skip();
            return hasNextByte();
        }
        
        public String next() {
            if (!hasNext())
                throw new NoSuchElementException();
            StringBuilder sb = new StringBuilder();
            int b = readByte();
            while (!isSpaceChar(b)) {
                sb.appendCodePoint(b);
                b = readByte();
            }
            return sb.toString();
        }
        
        public int nextInt() {
            if (!hasNext())
                throw new NoSuchElementException();
            int c = readByte();
            while (isSpaceChar(c))
                c = readByte();
            boolean minus = false;
            if (c == '-') {
                minus = true;
                c = readByte();
            }
            int res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res = res * 10 + c - '0';
                c = readByte();
            } while (!isSpaceChar(c));
            return (minus) ? -res : res;
        }
        
        public long nextLong() {
            if (!hasNext())
                throw new NoSuchElementException();
            int c = readByte();
            while (isSpaceChar(c))
                c = readByte();
            boolean minus = false;
            if (c == '-') {
                minus = true;
                c = readByte();
            }
            long res = 0;
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res = res * 10 + c - '0';
                c = readByte();
            } while (!isSpaceChar(c));
            return (minus) ? -res : res;
        }
        
        public double nextDouble() {
            return Double.parseDouble(next());
        }
        
        public int[] nextIntArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++)
                a[i] = nextInt();
            return a;
        }
        
        public long[] nextLongArray(int n) {
            long[] a = new long[n];
            for (int i = 0; i < n; i++)
                a[i] = nextLong();
            return a;
        }
        
        public char[][] nextCharMap(int n, int m) {
            char[][] map = new char[n][m];
            for (int i = 0; i < n; i++)
                map[i] = next().toCharArray();
            return map;
        }
    }
}

Measured memory_bytes: 21204