View Compilation Error

0_0_9731337_12179.cpp: In function `int main()':
0_0_9731337_12179.cpp:21: error: `u' undeclared (first use this function)
0_0_9731337_12179.cpp:21: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_9731337_12179.cpp:21: error: `v' undeclared (first use this function)