View Compilation Error

0_0_33843618_8778.cpp: In function 'int main()':
0_0_33843618_8778.cpp:17:16: error: too many arguments to function 'int len()'
   lengh=len(num);
                ^
0_0_33843618_8778.cpp:3:5: note: declared here
 int len();
     ^
0_0_33843618_8778.cpp:18:31: error: too many arguments to function 'int root()'
   printf("%d\n",root(num,lengh));
                               ^
0_0_33843618_8778.cpp:4:5: note: declared here
 int root();
     ^