reference to user is ambiguous

[anilsoni7]

i am trying to inherit user class to staff,account&customer class
but when i am trying to access the values of user it gives error

#include<iostream>
#include<fstream>
#include<ctime>
#include<iomanip>
#include<string>


using namespace std;

class User
{
private:
    char username[30];
    char name[30];
    char pass[30];
    string type;

public:
        void dep(int);
        void draw(int);
        string month(int a);
        void Title();
        void login();
        void intro();
};

class Customer:public User
{
private:
    char ac_type;
public:
    void customer();

};

class Account:public User
{

public:
        void create_account();  //for Creating new account
        void show_account()const;
        void modify();
        void report() const;
        int retAcno()const;
        int deposit()const;
        char retType()const;
};
class Staff:public Customer,public Account,public User
{
public:

void write_account();	
void display_sp(int);	
void modify_account(int);	
void delete_account(int);	
void display_all();		
void deposit_withdraw(int, int); 
void check();
};
void Staff::check()
{
    cout<<"Enter Username";
    cin.getline(username,30);
}


int main()
{
    user *u;
    staff s;
    u = &s;

    u->check();
}

[a10e29]

private:
    char username[30];
    char name[30];
    char pass[30];
    string type;

They are private, only that class can see them, you need gets() to access them