#include <iostream> #include <string> #include <queue> #include <stack> #include <algorithm> #include <list> #include <vector> #include <complex> #include <utility> #include <cstdio> #include <cstdlib> #include <cstring> #include <cmath> #include <climits> #include <bitset> #include <ctime> #include <map> #include <unordered_map> #include <set> #include <unordered_set> #include <cassert> #include <cstddef> #include <iomanip> #include <numeric> #include <tuple> #include <sstream> #include <fstream> #define REP(i,n) for(long (i)=0;(i)<(n);(i)++) #define FOR(i,a,b) for(long (i)=(a);(i)<(b);(i)++) #define RREP(i,a) for(long (i)=(a)-1;(i)>=0;(i)--) #define FORR(i,a,b) for(long (i)=(a)-1;(i)>=(b);(i)--) #define MOD 1000000007 #define PI acos(-1.0) #define DEBUG(C) cout<<C<<endl; #define VI vector<int> #define VL vector<long> #define VD vector<double> #define PII pair<int,int> #define PDD pair<double,double> #define PLL pair<long,long> #define ALL(a) (a).begin(),(a).end() #define SORT(a) sort((a).begin(),(a).end()) #define RSORT(a) sort((a).begin(),(a).end(),greater<int>()) #define MP(a,b) make_pair(a,b) #define FORE(a,b) for(auto &&a:b) typedef long long LL; typedef unsigned long long ULL; using namespace std; int main(void){ long x,y,d; cin>>x>>y>>d; if(!d){ cout<<1<<endl; return 0; } if(sqrt(x*x+y*y)<d){ cout<<0<<endl; }else{ cout<<2+(d*d/2)<<endl; } }