size(500,500);
background(255);

 //int c = 255;
 //int o = 0;
 
 //grid size change
int g =50;
 //grid
 int h=0;
 int i=0;
 for ( int a = 0; a<= g; a++){
   for ( int b = 0; b<= g; b++){
     rect( h,i,width/g,height/g);
     h= h+width/g;
   }
   i=i+height/g;
   h=0;
 }

stroke(0);
strokeWeight(3);
line(width*0.5,0,width*0.5,height*1);
line(0,height*0.5,width*1,height*0.5);

for (float x = 0; x<height; x = x+(width*0.05)) {
     line(width*0.49,x,width*0.51,x);
     for ( float y = 0; y<width; y = y+(height*0.05)){
        line(y,height*0.49,y,height*0.51);
     }
}
float p=width*0.5;
float q=height*0.5;
stroke(0,0,255);
strokeWeight(width*0.016);
point(p,q);

fill(0,0,255);
triangle(width*0.5,height*0.01,width*0.49,height*0.02,width*0.51,height*0.02);
triangle(width*0.5,height*0.984,width*0.49,height*0.974,width*0.51,height*0.974);
triangle(width*0.01,height*0.5,width*0.026,height*0.49,width*0.026,height*0.51);
triangle(width*0.99,height*0.5,width*0.964,height*0.49,width*0.964,height*0.51);


fill(255,0,0);
text("0",width*0.516,height*0.53);
float f =height*0.45;
 for( int u=1; u<=10; u=u+1){
   text(u,width*0.472,f);
   f = f-(height*0.05);
 }
  f = height*0.55;
 for( int u=-1; u>=-9; u=u-1){
   text(u,width*0.462,f);
   f = f+(height*0.05);
 }
 f = width*0.432;
 for( int u=-1; u>=-9; u=u-1){
   text(u,f,height*0.48);
   f = f-(width*0.05);
 }
 f = width*0.54;
 for( int u=1; u<=9; u=u+1){
   text(u,f,height*0.48);
   f = f+(width*0.05);
 }
save("Activity12.png");