#include <vector>
#include <iostream>

using namespace std;

int main(int argc, char* argv[]) {
  if (argc!=2) {
    cerr << "Need one argument." << endl;
    return EXIT_FAILURE;
  }
  int n=atoi(argv[1]);
  vector< vector<double> > M;
  M.reserve(n);
  for (int i=0; i<n; i++) {
    M.push_back(vector<double>());
    M.back().reserve(n);
    for (int j=0; j<n; j++) {
      M.back().push_back(i+j+2.5);
    }
  }
  double r=0;
  for (int i=0; i<n; i++) {
    for (int j=0; j<n; j++) {
      for (int k=0; k<n; k++) {
	r=r+M[i][k]*M[k][j];
      }
    }
  }
  cout << r << endl;
  return EXIT_SUCCESS;
}