View Compilation Error

0_0_2616015_12326.cpp: In function `int main()':
0_0_2616015_12326.cpp:39: error: `a' undeclared (first use this function)
0_0_2616015_12326.cpp:39: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_2616015_12326.cpp:48: error: `start' undeclared (first use this function)
0_0_2616015_12326.cpp:48: error: `end' undeclared (first use this function)