View Compilation Error

0_0_12354666_29083.cpp: In function `void ins(int, int)':
0_0_12354666_29083.cpp:15: error: `A' undeclared (first use this function)
0_0_12354666_29083.cpp:15: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_12354666_29083.cpp: In function `int find(int)':
0_0_12354666_29083.cpp:21: error: `A' undeclared (first use this function)
0_0_12354666_29083.cpp: In function `int main()':
0_0_12354666_29083.cpp:39: error: `A' undeclared (first use this function)