View Compilation Error

0_0_6657897_15748.cpp: In function `long long int getDown(int, int)':
0_0_6657897_15748.cpp:16: error: `yj' undeclared (first use this function)
0_0_6657897_15748.cpp:16: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6657897_15748.cpp:16: error: `yk' undeclared (first use this function)