/in/foo.cc: In function 'int main()':
/in/foo.cc:4:7: error: 'cin' was not declared in this scope
 while(cin>>m>>n)
       ^~~
/in/foo.cc:9:24: error: 'pow' was not declared in this scope
 sum-=pow(double(i)/m, n);
                        ^
/in/foo.cc:11:21: error: 'printf' was not declared in this scope
 printf("%.4f\n", sum);
                     ^