let a = 0;
for (a; a < 5; a++);
console.log(a);

let size = 5;
let a = 5;
for (let j = size; j >= 0; j=a) {
    document.write(a);
    a = a - 2;
}

var a = 0;
var b = 0;
while (a < 3)
{
    a++;
    b += a;
  console.log(b);
}