View Compilation Error

0_0_37146821_18663.cpp: In function 'int main()':
0_0_37146821_18663.cpp:17:9: error: cannot bind 'std::istream {aka std::basic_istream<char>}' lvalue to 'std::basic_istream<char>&&'
    cin>>c;
         ^
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/iostream:40:0,
                 from 0_0_37146821_18663.cpp:1:
GCC4.9.2/x86_64-w64-mingw32/include/c++/istream:872:5: note: initializing argument 1 of 'std::basic_istream<_CharT, _Traits>& std::operator>>(std::basic_istream<_CharT, _Traits>&&, _Tp&) [with _CharT = char; _Traits = std::char_traits<char>; _Tp = double [3000]]'
     operator>>(basic_istream<_CharT, _Traits>&& __is, _Tp& __x)
     ^
0_0_37146821_18663.cpp:18:11: error: invalid operands of types 'int' and 'double [3000]' to binary 'operator*'
    sum+=t*c;
           ^
0_0_37146821_18663.cpp:21:10: error: conflicting declaration 'double t'
   double t= n * a + b -2* sum;
          ^
0_0_37146821_18663.cpp:13:7: note: previous declaration as 'int t'
   int t=n;
       ^