int y_1 = 50;
int y_2 = 50;
int x_1 = 250;
int x_2 = 250;

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

background(255,255,255);
ellipse(x_1,y_1,25,25);

ellipse(x_2,y_2,25,25);

y_1 +=2;
y_2 +=2;
x_1 +=2;
x_2 -=2;

}