var x; 
var y;
var z; 
var a; 
var b;
z := readint();
x := 1;        // constant value
y := 2;        // not constant
x := 3;        // override
a := x + 4;    // compute constant
y := x + z;    // not constant
if y then
  z := 8;
  x := z - 5;  // constant
else
  x := a - 4;  // constant
  z := a + z;  // z is not constant
end
b := a + z;    // a still constant, z not
z := a + x;
writeint(b + z);