// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;



//def

#define debug(x) cout << #x << ": " << x << '\n'

#define out(x) cout << x << '\n'

#define repeat(i, a, b) for (int i = (int)(a); i < (int)(b); i++)

#define revrepeat(i, a, b) for (int i = (int)(b)-1; i >= (int)(a); i--)

#define rep(i, n) for (int i = 0; i < (int)(n); i++)

#define revrep(i, n) for (int i = (int)(n)-1; i >= 0; i--)

#define foreach(e, v) for (auto &e : v)

#define all(x) (x).begin(), (x).end()

#define CYES cout << "Yes" << endl

#define CNO cout << "No" << endl

#define SPC(x) cout << fixed << setprecision(x)

#define ZERO(a) memset(a, 0, sizeof(a))

#define MINUS(a) memset(a, 0xff, sizeof(a))



typedef long long ll;

typedef long double ld;

typedef vector<int> vi;

typedef vector<vector<int>> vii;

typedef vector<ll> vl;

typedef vector<vector<ll>> vll;

typedef pair<int, int> P;

constexpr int MOD = 1e9 + 7;

constexpr int INF = __INT_MAX__;               // 2^31 - 1

constexpr long long INFLL = __LONG_LONG_MAX__; // 2^61 - 1

constexpr int MAX_N = 1e5 + 5;

constexpr double PI = acos(-1);



template <class T>

inline bool chmin(T &a, T b) {

    if (a > b) {

        a = b;

        return true;

    }

    return false;

}

template <class T>

inline bool chmax(T &a, T b) {

    if (a < b) {

        a = b;

        return true;

    }

    return false;

}



long long fac[MAX_N], finv[MAX_N], inv[MAX_N];

// テーブルを作る前処理 from: https://qiita.com/drken/items/3b4fdf0a78e7a138cd9a

void COMinit() {

    fac[0] = fac[1] = 1;

    finv[0] = finv[1] = 1;

    inv[1] = 1;

    for (int i = 2; i < MAX_N; i++) {

        fac[i] = fac[i - 1] * i % MOD;

        inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;

        finv[i] = finv[i - 1] * inv[i] % MOD;

    }

}

long long modpow(long long m, long long p) {

    if (p == 0) return 1;

    if (p % 2)

        return m * modpow(m, p - 1) % MOD;

    else {

        long res = modpow(m, p / 2);

        return res * res % MOD;

    }

}

// 二項係数計算

long long COM(int n, int k) {

    if (n < k) return 0;

    if (n < 0 || k < 0) return 0;

    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;

}

// factorial

long long fact(int n) {

    if (n == 1) return fac[n] = 1;

    if (fac[n]) return fac[n];

    return fac[n] = (fact(n - 1) * n) % MOD;

}



// https://qiita.com/drken/items/cce6fc5c579051e64fab

// UnionFind<int> uf(n);

template <class Abel>

struct UnionFind {

    vector<int> par;

    vector<int> rank;

    vector<int> size;

    vector<Abel> diff_weight;



    UnionFind(int n = 1, Abel SUM_UNITY = 0) {

        init(n, SUM_UNITY);

    }



    void init(int n = 1, Abel SUM_UNITY = 0) {

        par.resize(n);

        rank.resize(n);

        size.resize(n);

        diff_weight.resize(n);

        for (int i = 0; i < n; ++i)

            par[i] = i, rank[i] = 0, size[i] = 1, diff_weight[i] = SUM_UNITY;

    }



    int root(int x) {

        if (par[x] == x) {

            return x;

        } else {

            int r = root(par[x]);

            diff_weight[x] += diff_weight[par[x]]; // path compression

            return par[x] = r;

        }

    }

    // returns size of connected-tree number

    int get_size(int x) {

        return size[root(x)];

    }



    Abel weight(int x) {

        root(x);

        return diff_weight[x];

    }



    bool is_same(int x, int y) {

        return root(x) == root(y);

    }



    bool merge(int x, int y, Abel w) {

        w += weight(x);

        w -= weight(y);

        x = root(x);

        y = root(y);

        if (x == y) return false;

        if (rank[x] < rank[y]) swap(x, y), w = -w;

        if (rank[x] == rank[y]) ++rank[x];

        par[y] = x;

        size[x] = size[y] = size[x] + size[y];

        diff_weight[y] = w;

        return true;

    }



    Abel diff(int x, int y) {

        return weight(y) - weight(x);

    }

};

long long gcd(long long a, long long b) {

    if (b == 0) return a;

    return gcd(b, a % b);

}



long long lcm(long long a, long long b) {

    return a / gcd(a, b) * b;

}



// factorization O(sqrt(n))

map<long long, long long> prime_factor(long long n) {

    map<long long, long long> res;

    for (long long i = 2; i * i <= n; i++) {

        while (n % i == 0) {

            ++res[i];

            n /= i;

        }

    }

    if (n != 1) res[n] = 1;

    return res;

}



// 回文判定

bool is_palindrome(string const &s) {

    return s == string(s.rbegin(), s.rend());

}



vi ans(100005);

vi seen(100005);

void dfs(int curr, int prev, int color, int color_size, vii &node, map<P, int> &dict) {

    seen[curr] = true;

    ans[dict[P(curr, prev)]] = color;

    foreach (e, node[curr]) {

        if (!seen[e]) {

            color++;

            if (color > color_size) color = 1;

            dfs(e, curr, color, color_size, node, dict);

        }

    }

}



int main() {

    int a, b, c;

    cin >> a >> b >> c;

    vi v = {a, b, c};

    sort(all(v));

    int ans = v[2] - v[1];

    ans += (v[1] - v[0]) % 2 == 0 ? (v[1] - v[0]) / 2 : (v[1] - v[0] + 1) / 2 + 1;

    out(ans);

}


// Faster C++ solution for the same problem (measured speedup: 1.8067309825133484x):
#include <bits/stdc++.h>

using namespace std;



// def

#define debug(x) cout << #x << ": " << x << endl

#define out(x) cout << x << endl

#define repeat(i, a, b) for (int i = (a); i < (b); i++)

#define revrepeat(i, a, b) for (int i = (b)-1; i >= (a); i--)

#define rep(i, n) for (int i = 0; i < (int)(n); i++)

#define revrep(i, n) for (int i = (n)-1; i >= 0; i--)

#define foreach(e, v) for (auto &e : v)

#define all(x) (x).begin(), (x).end()

#define CYES cout << "Yes" << endl

#define CNO cout << "No" << endl

#define SPC(x) cout << fixed << setprecision(x)

#define ZERO(a) memset(a, 0, sizeof(a))

#define MINUS(a) memset(a, 0xff, sizeof(a))



typedef long long ll;

typedef long double ld;

typedef vector<int> vi;

typedef vector<vector<int>> vii;

typedef vector<char> vc;

typedef vector<vector<char>> vcc;

typedef vector<ll> vl;

typedef vector<vector<ll>> vll;

typedef pair<int, int> P;

typedef vector<P> vp;

typedef vector<vector<P>> vpp;

typedef complex<ld> Point;

const int MOD = 1e9 + 7;

const int INF = 1e9;

const int MAX_V = 1e5 + 5;

const int MAX_N = 1e5 + 5;

const double PI = acos(-1);



template <class T>

inline bool chmin(T &a, T b) {

    if (a > b) {

        a = b;

        return true;

    }

    return false;

}

struct mint {

    // Preparation: MOD is alrejady defined.

    ll value;

    mint(ll value = 0) : value((value % MOD + MOD) % MOD) {}

    mint pow(ll t) const {

        if (!t) return 1;

        mint a = pow(t >> 1);

        a *= a;

        if (t & 1) a *= *this;

        return a;

    }

    mint pow(mint m) const {

        return pow(m.value);

    }

    mint inv() const {

        ll a = value, b = MOD, u = 1, v = 0;

        while (b) {

            ll t = a / b;

            a -= t * b;

            swap(a, b);

            u -= t * v;

            swap(u, v);

        }

        u %= MOD;

        return u;

    }

    mint &operator+=(const mint a) {

        if ((value += a.value) >= MOD) value -= MOD;

        return *this;

    }

    mint &operator-=(const mint a) {

        if ((value += MOD - a.value) >= MOD) value -= MOD;

        return *this;

    }

    mint &operator*=(const mint a) {

        (value *= a.value) %= MOD;

        return *this;

    }

    mint &operator/=(const mint a) {

        return (*this) *= a.inv();

    }

    mint operator+(const mint a) const {

        mint res(*this);

        return res += a;

    }

    mint operator-(const mint a) const {

        mint res(*this);

        return res -= a;

    }

    mint operator*(const mint a) const {

        mint res(*this);

        return res *= a;

    }

    mint operator/(const mint a) const {

        mint res(*this);

        return res /= a;

    }

};

template <class T>

inline bool chmax(T &a, T b) {

    if (a < b) {

        a = b;

        return true;

    }

    return false;

}



// make vector of divisor O(sqrt(n))

vector<long long> divisor(long long n) {

    vector<long long> res;

    for (long long i = 1; i * i <= n; i++) {

        if (n % i == 0) {

            res.push_back(i);

            if (i != n / i) res.push_back(n / i);

        }

    }

    return res;

}

bool is_prime(long long n) {

    for (long long i = 2; i * i <= n; i++) {

        if (n % i == 0) return false;

    }

    return n != 1; // exclude 1

}



// factorization O(sqrt(n))

map<long long, long long> prime_factor(long long n) {

    map<long long, long long> res;

    for (long long i = 2; i * i <= n; i++) {

        while (n % i == 0) {

            ++res[i];

            n /= i;

        }

    }

    if (n != 1) res[n] = 1;

    return res;

}

// https://qiita.com/drken/items/cce6fc5c579051e64fab

// UnionFind<int> uf(n);

template <class Abel>

struct UnionFind {

    vector<int> par;

    vector<int> rank;

    vector<int> size;

    vector<Abel> diff_weight;



    UnionFind(int n = 1, Abel SUM_UNITY = 0) {

        init(n, SUM_UNITY);

    }



    void init(int n = 1, Abel SUM_UNITY = 0) {

        par.resize(n);

        rank.resize(n);

        size.resize(n);

        diff_weight.resize(n);

        for (int i = 0; i < n; ++i)

            par[i] = i, rank[i] = 0, size[i] = 1, diff_weight[i] = SUM_UNITY;

    }



    int root(int x) {

        if (par[x] == x) {

            return x;

        } else {

            int r = root(par[x]);

            diff_weight[x] += diff_weight[par[x]]; // path compression

            return par[x] = r;

        }

    }

    // returns size of connected-tree number

    int get_size(int x) {

        return size[root(x)];

    }



    Abel weight(int x) {

        root(x);

        return diff_weight[x];

    }



    bool is_same(int x, int y) {

        return root(x) == root(y);

    }



    bool merge(int x, int y, Abel w) {

        w += weight(x);

        w -= weight(y);

        x = root(x);

        y = root(y);

        if (x == y) return false;

        if (rank[x] < rank[y]) swap(x, y), w = -w;

        if (rank[x] == rank[y]) ++rank[x];

        par[y] = x;

        size[x] = size[y] = size[x] + size[y];

        diff_weight[y] = w;

        return true;

    }



    Abel diff(int x, int y) {

        return weight(y) - weight(x);

    }

};

long long fac[MAX_N], finv[MAX_N], inv[MAX_N];

// テーブルを作る前処理 from: https://qiita.com/drken/items/3b4fdf0a78e7a138cd9a

void COMinit() {

    fac[0] = fac[1] = 1;

    finv[0] = finv[1] = 1;

    inv[1] = 1;

    for (int i = 2; i < MAX_N; i++) {

        fac[i] = fac[i - 1] * i % MOD;

        inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;

        finv[i] = finv[i - 1] * inv[i] % MOD;

    }

}

// 二項係数計算

long long COM(int n, int k) {

    if (n < k) return 0;

    if (n < 0 || k < 0) return 0;

    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;

}

// factorial

long long fact(int n) {

    if (n == 1) return fac[n] = 1;

    if (fac[n]) return fac[n];

    return fac[n] = (fact(n - 1) * n) % MOD;

}



long long gcd(long long a, long long b) {

    if (b == 0) return a;

    return gcd(b, a % b);

}



long long lcm(long long a, long long b) {

    return a / gcd(a, b) * b;

}



long long modpow(long long m, long long p) {

    if (p == 0) return 1;

    if (p % 2)

        return m * modpow(m, p - 1);

    else {

        long res = modpow(m, p / 2);

        return res * res;

    }

}



int main() {

    int a, b, c;

    cin >> a >> b >> c;

    int ma = max({a, b, c});

    int mi = min({a, b, c});

    int mid = a + b + c - ma - mi;

    int ans = 0;

    ans += ma - mid;

    if ((mid - mi) % 2 == 0) {

        ans += (mid - mi) / 2;

    } else {

        ans += (mid - mi + 1) / 2 + 1;

    }

    out(ans);

}