#include <stdio.h>
static const double grid[4][2] = {{-3 / 3., -1 / 3.},
{+1 / 3., -3 / 3.},
{-1 / 3., +3 / 3.},
{+3 / 3., +1 / 3.}};
int main() {
for (int i = 0; i < 4; i++)
printf("%d:%.2f,%.2f ", i, grid[i][0], grid[i][1]);
printf("\n");
return 0;
}