View Compilation Error

0_0_5153394_14486.cpp: In function `void dfs(int, int, int, int)':
0_0_5153394_14486.cpp:11: error: `tx' undeclared (first use this function)
0_0_5153394_14486.cpp:11: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_5153394_14486.cpp:11: error: `ty' undeclared (first use this function)