int x,y,xStep,yStep;
int jump;
void setup(){
  size(300,300);
  x=y=150;
  background(255);
  jump=1;
}

void draw(){

  xStep = int(random(99));
  yStep = int(random(99));


    if(xStep >= 50){
      x += jump;
    } else {
      x -= jump;
    }
      
    if(x<0){
      x=0;
    } else if (x>width){
      x=width;
    }
      
    if(yStep >= 50){
      y += jump;
    } else {
      y -= jump;
    }
    
    if(y<0){
      y=0;
    } else if (y>height){
      y=height;
    }
      
 
stroke(0,0,255);
 point(x,y);
   
}