void setup()
{
background(255,255,255);
size(500,500);
}

void draw()
{

}

void mouseClicked()
{
background(255,255,255);
int x = 0;
int y = 0;

for (int i1 = 0; i1 < 500; i1+=25)
{
for (int i2 = 0; i2 < 500; i2+=25)
{
int r = (int)(random(25));
rect(x+i1,y+i2,r,r);
}

}

}