View Compilation Error

0_0_6308732_15183.cpp: In function `void merge(int, int)':
0_0_6308732_15183.cpp:14: error: `x' undeclared (first use this function)
0_0_6308732_15183.cpp:14: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6308732_15183.cpp:14: error: `y' undeclared (first use this function)