new keys, updown, leftright;
GetPlayerKeys(playerid,updown,leftright);

if(updown<0){
        // When they press Up.
        //Up has a value of -128, which is LESS THAN (<) 0  
}
else {
        // When they press Down.
        //Up has a value of 128, which is NOT LESS THAN (<) 0  
}
if(leftright<0){
        // When they press Left.
        //Left has a value of -128, which is LESS THAN (<) 0  
}
else {
        // When they press Right.
        //Right has a value of 128, which is NOT LESS THAN (<) 0  
}