View Compilation Error

0_0_5487738_3037.cpp: In function `int main()':
0_0_5487738_3037.cpp:23: error: `left' undeclared (first use this function)
0_0_5487738_3037.cpp:23: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_5487738_3037.cpp:23: error: `right' undeclared (first use this function)