View Compilation Error

0_0_16870824_23586.cpp: In function 'long long int num(int)':
0_0_16870824_23586.cpp:21:20: error: ambiguating new declaration of 'long long int num(int)'
 long long num(int n)
                    ^
0_0_16870824_23586.cpp:6:5: note: old declaration 'int num(int)'
 int num(int n);
     ^