Expected Unqualified ID before if (c++ error)

(*I know this question has been answered before on Stack Overflow, but none of those answers worked for me)

I am creating a sort of banking game (text only) using basic c++. I am getting an error on one of my if statements when trying to create a function that allows the user to deposit money in one of the 4 vaults. The error is:

main.cpp: In member function 'int bank::moneyChange::deposit_money()':
main.cpp:58:10: error: 'vaultNum' was not declared in this scope
       if(vaultNum == 1) {

I am trying to figure out how I can get the scope to extend to the moneyChange class.

My C++:

#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>

using namespace std;

class bank {
  class bankName{
    public:
    string bank_name(string) {

      string bank_name;
      cout << "Choose your bank name! : ";
      cin >> bank_name;
      return bank_name;

    }
  };
  class vaults{
    public:
    int findVault(){
      int vaultNum;
      cout << "Which vault do you want to open? (1, 2, 3, or 4 ?)" << endl;
      cin >> vaultNum;
      if(vaultNum == 1) {
        vaultNum = 1;
        return vaultNum;
      }
      else if(vaultNum == 2) {
        vaultNum == 2;
        return vaultNum;
      }
      else if(vaultNum == 3) {
        vaultNum == 3;
        return 0;
      }
      else if(vaultNum == 4){
        vaultNum == 4;
        return 0;
      }
      else{
        cout << "Did you choose a valid number? (1, 2, 3, or 4) " << endl;
        findVault();
      }


  }
 };
  class moneyChange{
    public:
      int vaultnumber1Money = 250000;
      int depositAmount;
      if(vaultNum == 1) {
      cout << "Vault Number 1 has 250000 dollars in the bank" << endl;
      cout << "How much money do you want to deposit?" << endl;
      cin >> depositAmount;
      int vaultnumber1Money = vaultnumber1Money + depositAmount;
      return vaultnumber1Money;
    }
    }
  };
  };














int main()
{
}
};