#include <iostream>
#include <math.h>
using namespace std;

const int dim=3; // dimension
const int n=4; // no. of particles
double r[n][dim] = { {0,0,6},{1,5,2},{3,3,3},{5,2,6} }; // coordinates

int main(){
  double rsum[dim]; // sum of coordinates
  double rc[dim];   // position of center of mass 

  for (int u=0; u<dim; ++u){ // u-th dimension
    rsum[u]=0;
    for (int i=0; i<n; ++i){ // i-th particle
      rsum[u] += r[i][u];
    }
    rc[u] = rsum[u]/n;  // position of center of mass 
    cout << rc[u] << ' ';
  }
  cout << endl;
}