View Compilation Error

0_0_5150319_19273.cpp: In function `int main()':
0_0_5150319_19273.cpp:8: error: `Y1' undeclared (first use this function)
0_0_5150319_19273.cpp:8: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_5150319_19273.cpp:8: error: `Y2' undeclared (first use this function)