View Compilation Error

0_0_18881244_10155.cpp: In function 'void gadd(T1&, T2)':
0_0_18881244_10155.cpp:25:76: error: 'Z' was not declared in this scope
 template <class T1, class T2>inline void gadd(T1 &a, T2 b) { a = (a + b) % Z; }
                                                                            ^