View Compilation Error

0_0_32631802_18418.cpp: In function 'bool in(const point&, const std::vector<point>&)':
0_0_32631802_18418.cpp:15:23: error: invalid initialization of reference of type 'point&' from expression of type 'const value_type {aka const point}'
         point &p = g[i];
                       ^
0_0_32631802_18418.cpp:16:23: error: invalid initialization of reference of type 'point&' from expression of type 'const value_type {aka const point}'
         point &q = g[j];
                       ^