foo.cc: In function 'int main()':
foo.cc:9:67: error: too few arguments to function 'long long int power(int, int, int)'
     cout << a << '^' << b << " mod " << p << '=' << power(a % p, b) % 10;
                                                                   ^
foo.cc:4:11: note: declared here
 long long power(int a, int b,int m);
           ^~~~~

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