int x = 50;
int dir = 3;
int s = 0;
int d = 3;
void setup(){
  size(600,600);
  background(255);
  textSize(30);
}
void draw(){
  background(255);
  x = constrain(x,40,580);
fill(255,0,0);
ellipse(x,150,60,60);
fill(150,0,255);
text("x= " +x,x-80,50);

x = x + dir;
}
void mousePressed(){
  s = s * -1;
  dir = dir * -1;
  d = d * -1;
}
void keyPressed(){
  s = s + d;
  dir = dir + s;
  
}