View Compilation Error

0_0_4330442_19437.cpp: In function `int main()':
0_0_4330442_19437.cpp:23: error: `z' undeclared (first use this function)
0_0_4330442_19437.cpp:23: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_4330442_19437.cpp:31: error: `x' undeclared (first use this function)