View Compilation Error

0_0_15234102_18646.cpp:1:1: error: 'f' does not name a type
 f[0]=0;
 ^
0_0_15234102_18646.cpp:2:1: error: expected unqualified-id before 'for'
 for(int i=1; i<=400002; i++) 
 ^
0_0_15234102_18646.cpp:2:14: error: 'i' does not name a type
 for(int i=1; i<=400002; i++) 
              ^
0_0_15234102_18646.cpp:2:25: error: 'i' does not name a type
 for(int i=1; i<=400002; i++) 
                         ^
0_0_15234102_18646.cpp: In function 'double logC(int, int)':
0_0_15234102_18646.cpp:6:12: error: 'f' was not declared in this scope
     return f[m]-f[n]-f[m-n];
            ^