C 变量的作用域

下面的程序输出什么？思考一下

#include <stdio.h>
 
// Driver Code
int main()
{
    {
        int x = 10, y = 20;
        {
            // The outer block contains
            // declaration of x and
            // y, so following statement
            // is valid and prints
            // 10 and 20
            printf("x = %d, y = %d\n", x, y);
            {
                // y is declared again,
                // so outer block y is
                // not accessible in this block
                int y = 40;
 
                // Changes the outer block
                // variable x to 11
                x++;
 
                // Changes this block's
                // variable y to 41
                y++;
 
                printf("x = %d, y = %d\n", x, y);
            }
 
            // This statement accesses
            // only outer block's
            // variables
            printf("x = %d, y = %d\n", x, y);
        }
    }
    return 0;
}

Output: 

x = 10, y = 20
x = 11, y = 41
x = 11, y = 20

实例代码来自：https://www.geeksforgeeks.org/scope-rules-in-c/