View Compilation Error

0_0_37759680_8730.cpp: In instantiation of 'int fft::sz(const T&) [with T = std::vector<modnum>]':
0_0_37759680_8730.cpp:45:16:   required from here
0_0_37759680_8730.cpp:38:61: error: 'size' was not declared in this scope
 template <typename T> int sz(const T& a) { return int(size(a)); }
                                                             ^
0_0_37759680_8730.cpp: In instantiation of 'int fft::sz(const T&) [with T = std::vector<int>]':
0_0_37759680_8730.cpp:62:30:   required from here
0_0_37759680_8730.cpp:38:61: error: 'size' was not declared in this scope