View Compilation Error

0_0_3825887_993.cpp: In function `int main()':
0_0_3825887_993.cpp:9: error: `n' undeclared (first use this function)
0_0_3825887_993.cpp:9: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_3825887_993.cpp:10: error: `an' undeclared (first use this function)
0_0_3825887_993.cpp:26: error: `b' undeclared (first use this function)
0_0_3825887_993.cpp:27: error: `recur' undeclared (first use this function)