Palindrome wordlist generators C++ ultra simple

I'm not going great lenghts to explain this one. I think I have a better example that I will post in a bit. I'm still cleaning out my code folder.

#include <iostream>

using namespace std;
int a;
int b;
int c;
int d;

}
}
//4 character palindromes
for (a=0; a <= 9; a++){
for (b=0; b <= 9; b++){
cout << b << a << a << b << endl;
}
}
}