#include <iostream>
#include <algorithm>
using namespace std;

class range {private: struct I{int x;int operator*(){return x;}bool operator!=(I& lhs){return x<lhs.x;}void operator++(){++x;}};I i,n;
public:range(int n):i({0}),n({n}){}range(int i,int n):i({i}),n({n}){}I& begin(){return i;}I& end(){return n;}};

int main(void) {
  vector<int> v(3);
  for(int i : range(3)) { scanf("%d", &v[i]); }
  sort(v.begin(), v.end());
  int lo = v[0], hi = v[2];
  while(hi - lo > 1) {
    int md = (lo + hi) / 2;
    int taran = md - v[0],
        amaru = (v[2] - md) / 2;
    if(md > v[1]) {
      taran += md - v[1];
    } else {
      amaru += (v[1] - md) / 2;
    }
    if(amaru >= taran) {
      lo = md;
    } else {
      hi = md;
    }
  }
  printf("%d\n", lo);
  return 0;
}