View Compilation Error

0_0_32607963_10816.cpp:3:41: error: redefinition of 'long long int n'
 long long exp_mod(long long n,long long n,long long b)
                                         ^
0_0_32607963_10816.cpp:3:29: note: 'long long int n' previously declared here
 long long exp_mod(long long n,long long n,long long b)
                             ^
0_0_32607963_10816.cpp: In function 'long long int exp_mod(long long int, long long int)':
0_0_32607963_10816.cpp:8:22: error: too many arguments to function 'long long int exp_mod(long long int, long long int)'
     t=exp_mod(n,n/2,b);
                      ^
0_0_32607963_10816.cpp:3:11: note: declared here
 long long exp_mod(long long n,long long n,long long b)
           ^
0_0_32607963_10816.cpp: In function 'int main()':
0_0_32607963_10816.cpp:22:29: error: too many arguments to function 'long long int exp_mod(long long int, long long int)'
         cout<<exp_mod(n,n,10)<<endl;
                             ^
0_0_32607963_10816.cpp:3:11: note: declared here
 long long exp_mod(long long n,long long n,long long b)
           ^