Currently, the multisig descriptor constructions are limited to 16 keys only possibly because of template parsing reasons. Under p2sh context, such scripts would be invalid anyway because of 520-byte rule, but we can support up to 20 keys for CHECKMULTISIG in witness script context. 


{
                    
                    CScriptNum bn(stack.size());
                    stack.push_back(bn.getvch());
                }
                break;
                case OP_DROP:
                {
                    
                    if (stack.size() < 1)
                        return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
                    popstack(stack);
                }
                break;
                case OP_DUP:
                {
                    
                    if (stack.size() < 1)
                        return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
                    valtype vch = stacktop(-1);
                    stack.push_back(vch);
                }
                break;
                case OP_NIP:
                {
                    
                    if (stack.size() < 2)
                        return set_error(serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
                    stack.erase(stack.end() - 2);
                }