/in/foo.cc: In function 'int main()':
/in/foo.cc:15:7: error: no matching function for call to 'sort()'
  sort()
       ^
In file included from /usr/include/c++/6/algorithm:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:65,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_algo.h:4697:5: note: candidate: template<class _RAIter> void std::sort(_RAIter, _RAIter)
     sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
     ^~~~
/usr/include/c++/6/bits/stl_algo.h:4697:5: note:   template argument deduction/substitution failed:
/in/foo.cc:15:7: note:   candidate expects 2 arguments, 0 provided
  sort()
       ^
In file included from /usr/include/c++/6/algorithm:62:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:65,
                 from /in/foo.cc:1:
/usr/include/c++/6/bits/stl_algo.h:4727:5: note: candidate: template<class _RAIter, class _Compare> void std::sort(_RAIter, _RAIter, _Compare)
     sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
     ^~~~
/usr/include/c++/6/bits/stl_algo.h:4727:5: note:   template argument deduction/substitution failed:
/in/foo.cc:15:7: note:   candidate expects 3 arguments, 0 provided
  sort()
       ^
/in/foo.cc:17:2: error: 'ans' was not declared in this scope
  ans.l=a[1].l;
  ^~~
/in/foo.cc:19:14: error: 'i' was not declared in this scope
  for(int i=2;i<=n;i++){
              ^