View Compilation Error

0_0_23919821_1539.cpp: In function 'void Solve()':
0_0_23919821_1539.cpp:1:21: error: 'acos' was not declared in this scope
 #define pi acos(-1.0)  
                     ^
0_0_23919821_1539.cpp:16:24: note: in expansion of macro 'pi'
     double R = 20000.0/pi;  
                        ^
0_0_23919821_1539.cpp:18:32: error: 'scanf' was not declared in this scope
     while(~scanf("%d%d", &n, &m))  
                                ^
0_0_23919821_1539.cpp:45:27: error: 'printf' was not declared in this scope
         printf("%d\n", cnt);  
                           ^