background(207, 207, 207);
line(200,0,200,400);
line(0,200,400,200);

stroke(224, 224, 224);
for(var x = 0; x <= 400; x +=10){
    line(x, 0, x, 400);
}
for(var y = 0; y <= 400; y +=10){
    line(0, y, 400, y);
}

stroke(0, 0, 0);
line(200,0,200,400);
line(0,200,400,200);

stroke(255, 15, 15);
var x = 0;

stroke(255, 0, 0);
for(var x = -200; x <= 200; x++){
    y = (-1*(Math.pow(x,2)) + x*4 + 4);
    point(x+200,y+200);
}