#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;

}