heres my script

var health = 60;
var something : GameObject;

function OnTriggerEnter(thing: Collider){
    if (thing.name == "Bullet"){
    health - 1;
    }
    else
    if (thing.name == "FlameBall"){
    health - 3;
    }
    else
    if (thing.name == "Bomb"){
    health - 6;
    }
    }

    function Update () {
    if (health <= 0)
    Destroy (something);
    }
i have 3 bce0034 errors, one at the first minus, one at the second and one at the semicolon after the 3rd minus

help plz