float x1 = x[0];
float y1 = x[1];
float z1 = x[2];

float upper = R_int(-(z1-15)- fabs(x1), -(z1-15) - fabs(y1));
float lower = R_int((z1+15)- fabs(x1), (z1+15) - fabs(y1));

return R_int(upper, lower);