int a = 20%100;         // Sets a to 20 
int b = 20%100;         // Sets b to 20 
float c = 75.0%100.0;   // Sets c to 75.0 
float d = 275.0%100.0;  // Sets d to 75.0 

float a = 0.0; 
void draw() { 
  background(204); 
  a = (a + 0.5)%width; 
  line(a, 0, a, height); 
}