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

int main()
{
  cout << 10./3. << endl; // 6 significant figures by default
  cout << setprecision(3) << 10./3. << endl; // 3 significant figures
  cout << setprecision(15) << 10./3. << endl;
  cout << setprecision(20) << 10./3. << endl; // seeing machine errors
}