// 2 dimensional array, with function for picture and recursive print
#include <iostream>
using namespace std;

void changeState(bool picture[][21], int indent, int rows, int cols) {
   for (int r = indent; r <= rows -1 - indent; r++)
      for (int c = indent; c <= cols - 1 - indent; c++)
          picture[r][c] = !picture[r][c];
}

void print(bool picture[][21], int rows, int cols) {
   if (rows > 1) print(picture, rows - 1, cols);
   for (int c = 0; c < cols; c++) 
      if (picture[rows - 1][c]) cout << "*";
      else cout << " ";
   cout << endl;
}

int main() {
   bool picture[21][21];
   for (int r = 0; r <= 20; r++)
      for (int c = 0; c <= 20; c++) picture[r][c] = true;
   for (int indent = 1; indent <= 10; indent++) 
      changeState(picture, indent, 21, 21);
   print(picture, 21, 21);
   return 0;
}