View Compilation Error

0_0_8793548_8293.cpp: In member function `void Edge::add(int, int)':
0_0_8793548_8293.cpp:27: error: `u' undeclared (first use this function)
0_0_8793548_8293.cpp:27: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_8793548_8293.cpp: In function `int main()':
0_0_8793548_8293.cpp:109: error: `add' undeclared (first use this function)