View Compilation Error

0_0_10613219_25916.cpp: In function `int fun(int)':
0_0_10613219_25916.cpp:4: error: `y0' undeclared (first use this function)
0_0_10613219_25916.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_10613219_25916.cpp:4: error: stray '@' in program
0_0_10613219_25916.cpp:4: error: expected `)' before numeric constant