foo.cc: In function ‘int main()’:
foo.cc:49:27: warning: ‘x’ may be used uninitialized [-Wmaybe-uninitialized]
   49 |                 if(!f[x][y])
      |                     ~~~~~~^
foo.cc:14:21: note: ‘x’ was declared here
   14 |                 int x,y;
      |                     ^
foo.cc:49:27: warning: ‘y’ may be used uninitialized [-Wmaybe-uninitialized]
   49 |                 if(!f[x][y])
      |                     ~~~~~~^
foo.cc:14:23: note: ‘y’ was declared here
   14 |                 int x,y;
      |                       ^