/in/foo.cc: In function 'int main()':
/in/foo.cc:10:12: warning: unused variable 'l' [-Wunused-variable]
  int i,j,k,l;
            ^
/in/foo.cc:44:25: warning: 'mark' may be used uninitialized in this function [-Wmaybe-uninitialized]
  if (mark!=0) cout<<mark;
                         ^