foo.cc: In function ‘bool cmp(t, t)’:
foo.cc:13:33: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses]
   13 |         return a.x<b.x||a.x==b.x&&a.y<b.y;
      |                         ~~~~~~~~^~~~~~~~~
foo.cc: In function ‘int read()’:
foo.cc:16:15: warning: unused variable ‘f’ [-Wunused-variable]
   16 |         int x,f;
      |               ^
foo.cc: In function ‘int main()’:
foo.cc:41:33: warning: unused variable ‘u’ [-Wunused-variable]
   41 |                         int k,l,u;k=read();l=read();
      |                                 ^
foo.cc: In function ‘int read()’:
foo.cc:20:20: warning: ‘x’ may be used uninitialized [-Wmaybe-uninitialized]
   20 |                 x=x*10+ch-'0';
      |                   ~^~~
foo.cc:16:13: note: ‘x’ was declared here
   16 |         int x,f;
      |             ^
In function ‘int read()’,
    inlined from ‘int main()’ at foo.cc:38:15:
foo.cc:20:20: warning: ‘x’ may be used uninitialized [-Wmaybe-uninitialized]
   20 |                 x=x*10+ch-'0';
      |                   ~^~~
foo.cc: In function ‘int main()’:
foo.cc:16:13: note: ‘x’ was declared here
   16 |         int x,f;
      |             ^
In function ‘int read()’,
    inlined from ‘int main()’ at foo.cc:41:20:
foo.cc:20:20: warning: ‘x’ may be used uninitialized [-Wmaybe-uninitialized]
   20 |                 x=x*10+ch-'0';
      |                   ~^~~
foo.cc: In function ‘int main()’:
foo.cc:16:13: note: ‘x’ was declared here
   16 |         int x,f;
      |             ^
In function ‘int read()’,
    inlined from ‘int main()’ at foo.cc:41:29:
foo.cc:20:20: warning: ‘x’ may be used uninitialized [-Wmaybe-uninitialized]
   20 |                 x=x*10+ch-'0';
      |                   ~^~~
foo.cc: In function ‘int main()’:
foo.cc:16:13: note: ‘x’ was declared here
   16 |         int x,f;
      |             ^