foo.c:4:1: warning: missing braces around initializer [-Wmissing-braces]
 int a[9][9]={0};
 ^
foo.c:4:1: warning: (near initialization for 'a[0]') [-Wmissing-braces]
foo.c:5:1: warning: missing braces around initializer [-Wmissing-braces]
 bool mark=false,ka[9][9]={0},kb[9][9]={0},kc[3][3][9]={0};
 ^
foo.c:5:1: warning: (near initialization for 'ka[0]') [-Wmissing-braces]
foo.c:5:1: warning: missing braces around initializer [-Wmissing-braces]
foo.c:5:1: warning: (near initialization for 'kb[0]') [-Wmissing-braces]
foo.c:5:1: warning: missing braces around initializer [-Wmissing-braces]
foo.c:5:1: warning: (near initialization for 'kc[0]') [-Wmissing-braces]
foo.c: In function 'work':
foo.c:13:9: error: 'for' loop initial declarations are only allowed in C99 mode
         for (int i=0;i<9;i++)
         ^
foo.c:13:9: note: use option -std=c99 or -std=gnu99 to compile your code
foo.c:15:13: error: 'for' loop initial declarations are only allowed in C99 mode
             for (int j=0;j<9;j++)
             ^
foo.c:23:5: error: 'for' loop initial declarations are only allowed in C99 mode
     for (int i=8;i>=0;i--)
     ^
foo.c: In function 'main':
foo.c:50:9: error: 'for' loop initial declarations are only allowed in C99 mode
         for (int i=0;i<9;i++)
         ^
foo.c:53:13: error: 'for' loop initial declarations are only allowed in C99 mode
             for (int j=0;j<9;j++)
             ^