/in/foo.cc: In function 'long long int power(long long int, long long int)':
/in/foo.cc:10:9: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
         if ( b % 2 ) 
         ^~
/in/foo.cc:12:3: note: ...this statement, but the latter is misleadingly indented as if it is guarded by the 'if'
   r=r%o;
   ^
/in/foo.cc:12:7: error: 'o' was not declared in this scope
   r=r%o;
       ^
/in/foo.cc:17:14: error: 'o' was not declared in this scope
     return r%o;
              ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:28:25: error: 'o' was not declared in this scope
  ans=((powerr-arr(m,n))%o+o)%o;
                         ^