View Compilation Error

0_0_23238745_21014.cpp: In function 'int main()':
0_0_23238745_21014.cpp:18:49: error: 'strcmp' was not declared in this scope
         else if(b[max]==b[i]&&strcmp(a[max],a[i])>0)
                                                 ^
0_0_23238745_21014.cpp: In function 'long long int prime(long long int)':
0_0_23238745_21014.cpp:25:28: error: ambiguating new declaration of 'long long int prime(long long int)'
 long long prime(long long n){
                            ^
0_0_23238745_21014.cpp:3:5: note: old declaration 'int prime(long long int)'
 int prime(long long n);
     ^