View Compilation Error

0_0_2606445_23592.cpp: In function `int main()':
0_0_2606445_23592.cpp:11: error: `da' undeclared (first use this function)
0_0_2606445_23592.cpp:11: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_2606445_23592.cpp:12: error: `n' undeclared (first use this function)
0_0_2606445_23592.cpp:14: error: `a' undeclared (first use this function)