diff --git a/contracts/connectors/authority.sol b/contracts/connectors/authority.sol
index ee5b8fd..1eca8c5 100644
--- a/contracts/connectors/authority.sol
+++ b/contracts/connectors/authority.sol
@@ -1,4 +1,5 @@
 pragma solidity ^0.6.0;
+pragma experimental ABIEncoderV2;
 
 /**
  * @title ConnectAuth.
@@ -14,6 +15,39 @@ interface EventInterface {
     function emitEvent(uint _connectorType, uint _connectorID, bytes32 _eventCode, bytes calldata _eventData) external;
 }
 
+interface ListInterface {
+    struct UserLink {
+        uint64 first;
+        uint64 last;
+        uint64 count;
+    }
+
+    struct UserList {
+        uint64 prev;
+        uint64 next;
+    }
+
+    struct AccountLink {
+        address first;
+        address last;
+        uint64 count;
+    }
+
+    struct AccountList {
+        address prev;
+        address next;
+    }
+
+    function accounts() external view returns (uint);
+    function accountID(address) external view returns (uint64);
+    function accountAddr(uint64) external view returns (address);
+    function userLink(address) external view returns (UserLink memory);
+    function userList(address, uint64) external view returns (UserList memory);
+    function accountLink(uint64) external view returns (AccountLink memory);
+    function accountList(uint64, address) external view returns (AccountList memory);
+
+}
+
 
 contract Basics {
 
@@ -24,17 +58,31 @@ contract Basics {
         return 0x2af7ea6Cb911035f3eb1ED895Cb6692C39ecbA97;
     }
 
+    /**
+     * @dev Return InstaList Address.
+    */
+    function getListAddr() internal pure returns (address) {
+        return 0x4c8a1BEb8a87765788946D6B19C6C6355194AbEb;
+    }
+
      /**
      * @dev Connector ID and Type.
      */
     function connectorID() public pure returns(uint _type, uint _id) {
-        (_type, _id) = (1, 10);
+        (_type, _id) = (1, 37);
     }
 
 }
 
+contract Helpers is Basics {
+    function checkAuthCount() internal view returns (uint count) {
+        ListInterface listContract = ListInterface(getListAddr());
+        uint64 accountId = listContract.accountID(address(this));
+        count = listContract.accountLink(accountId).count;
+    }
+}
 
-contract Auth is Basics {
+contract Auth is Helpers {
 
     event LogAddAuth(address indexed _msgSender, address indexed _authority);
     event LogRemoveAuth(address indexed _msgSender, address indexed _authority);
@@ -59,6 +107,7 @@ contract Auth is Basics {
      * @param authority authority Address.
      */
     function remove(address authority) external payable {
+        require(checkAuthCount() > 1, "Removing-all-authorities");
         AccountInterface(address(this)).disable(authority);
 
         emit LogRemoveAuth(msg.sender, authority);