Consider the following operations performed on a Stack with array implementation of size $10.$ How many elements stay in the stack after all these operations?

StackArray stack $=$ new StackArray $(10)$;

stack.push$(11)$;

stack.push$(21)$;

stack.pop$()$;

stack.push$(31)$;

stack.push$(41)$;

stack.push$(51)$;

stack.pop$()$;

stack.push$(61)$;

stack.push$(77)$;

Your answer:

$4$

$5$

$6$

$7$