#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
typedef long long ll;
using namespace __gnu_pbds;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;
#pragma GCC target ("avx2")
#pragma GCC optimization ("O3")
#pragma GCC optimization ("unroll-loops")
#define ios ios_base::sync_with_stdio(0) ; cin.tie(0) ; cout.tie(0)
#define so sizeof
#define pb push_back
#define cl clear() ;
#define vl vector<ll>
#define sz size()
#define len length()
#define emp empty()
#define el endl;cout.flush()
#define be begin()
#define fi first
#define se second
#define br break
#define en end()
#define ro return 0
#define eb emplace_back
#define con continue
#define ms(x) memset(x , 0, so x)
#define all(x) (x).be , (x).en
#define acc(x) accumulate((x).be , (x).en , 0ll)
#define forn(i,a,b) for(ll i=a;i<=b;++i)
#define rng_58 mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define vll vector<pair<ll,ll> >
#define pll pair<ll,ll>
#define plll pair<ll,pair<ll,ll>>
#define plvl pair<pair<ll,ll> ,ll>
#define mp make_pair
#define trace3(a,b,c) cerr <<"a is " << a << " b is " << b << " c is " << c << el;
#define trace4(a,b,c,d) cerr <<"a is " << a << " b is " << b << " c is " << c <<" d is " << d << el ;
#define trace5(a,b,c,d,e) cerr <<"a is " << a << " b is " << b << " c is " << c <<" d is " << d << " e is " << e << el;
#define trace6(a,b,c,d,e,f) cerr <<"a is " << a << " b is " << b << " c is " << c <<" d is " << d << " e is " << e << " f is " << f << el ;

int main()
{
    ios;
    ll a , b , c;
    cin >> a >> b >> c;
    vl v;
    v.pb(a) ; v.pb(b) ; v.pb(c) ;
    sort(all(v));
    ll maxx = v[2] ;
    a = v[0] ; b = v[1] ;
    c = v[2] ;
    if(c % 2 == 0 ) {
        if(a % 2 == 1 and b % 2 == 1){
            ll x1 = 0 , x2 = 0 ;
            x1 = (c - a ) / 2 ;
            x2 = (c - b ) / 2 ;
            ll foo = 0 ;
            foo = foo + x1 + x2 ;
            ++foo ;
            cout << foo << el;
            ro ;
        }
        else if (a% 2 == 1 and b % 2 == 0 ) {
            ll x1 = 0 ;
            x1 = (c - a ) / 2;
            ll x2 = 0 ;
            x2 = (c - b) / 2 ;
            ll foo = x1 + x2 ;
            ++foo;
            ++foo;
            cout << foo << el ;
            ro ;
        }
        else if(a % 2 == 0 and b % 2 == 1){
            ll x1 = (c - a) /2 ;
            ll x2 = (c - b) / 2 ;
            ll foo = x1 + x2 ;
            ++foo ;
            ++foo ;
            cout << foo << el ;
            ro ;
        }
        else if(a % 2 == 0 and b % 2 == 0){
             ll x1 = (c - a) / 2 ;
             ll x2 = (c - b) / 2 ;
             ll foo = x1 + x2;
             cout << foo << el ;
             ro ;
        }
    }
    else if(c % 2 == 1){
         if(a % 2 == 1 and b % 2 == 1){
            ll x1 = (c-a) / 2;
            ll x2 = (c-b) / 2 ;
            ll foo = x1 + x2 ;
            cout << foo << el ;
            ro ;
         }
         else if(a % 2 == 1 and b % 2 == 0 ){
             ll x1 =  (c - a) / 2 ;
             ll x2 = (c - b ) / 2 ;
             ll foo = x1 + x2 ;
             ++foo ;
             ++foo ;
             cout << foo  << el;
             ro ;
         }
         else if(a % 2 == 0 and b % 2 == 1){
            ll x1 = (c - a ) / 2 ;
            ll x2 = (c - b) /   2;
            ll foo = x1 +  x2 ;
            ++foo ;
            ++foo;
            cout << foo << el ;
            ro;
         }
         else if(a % 2 == 0 and b % 2 == 0 ) {
            ll x1 = ( c - a )  / 2 ;
            ll x2 = ( c -  b ) / 2 ;
            ll foo = x1 + x2 ;
            ++foo ;
            cout << foo << el;
            ro ;
         }
    }
    ro  ;
}































Measured memory_bytes: 256