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int a = 1;
int b = 900;
void setup(){
size(900,450);
background(0);
smooth();
}
void draw(){
noStroke();
fill(random(55,200),0,0,20);
rectMode(CENTER);
rect(a, 225, random(0,100),random(0,400));
fill(random(55,200),0,0,20);
rectMode(CENTER);
rect(b, 225, random(0,100),random(0,400));
a = a + 3;
b = b - 3;
}