I cant understand why I am getting this kind of error. please help me out [closed]

error: cannot call member function 'singleton* singleton::create(char)' without object
s1 = singleton::create(x);
                ^
test.cpp:27:29: error: cannot call member function 'singleton* singleton::create(char)' without object
s2 = singleton::create(y);
                ^

#include <iostream>
using namespace std;

class singleton
{
    char c;
    static singleton *object; 
    singleton(char x) : c(x) {}
     
public:
    singleton *create(char x)
    { 
        if (!object)
            object = new singleton(x);
        return object;
    }
    void show();
};
    
singleton *singleton ::object = 0; 

void singleton::show()
{
    cout << c;
}
    
int main()
{
    char x, y;
    singleton *s1, *s2;
    cin >> x >> y;
    s1 = singleton::create(x);
    s2 = singleton::create(y);
    s1->show();
    s2->show();
    return 0;
}