#include using namespace std; #define rep(i,n) for(int i=0;i<(int)(n);i++) #define repi(i,a,b) for(int i=(int)(a);i<(int)(b);i++) #define all(x) (x).begin(),(x).end() #define foreach(u,v) for(auto (u) : (v)) #define pb push_back #define mp make_pair #define mt make_tuple #define int long long typedef long long ll; typedef pair pii; typedef vector vi; typedef vector vvi; typedef pair pll; typedef vector vl; const int inf = 1e9; const ll linf = 1LL<<60; const ll mod = 1e9 + 7; const double eps = 1e-9; /* u = x + y, v = x - y d = max(|u|, |v|); */ signed main() { int x, y, d; cin >> x >> y >> d; int u = x+y; int v = x-y; if(u < d) cout << 0 << endl; else cout << min(abs(u), d+1) + min(abs(v), d+1) << endl; return 0; }