foo.cc: In function 'int main()':
foo.cc:5:14: error: 'cin' was not declared in this scope
    5 |     double a;cin>>a;int k;cin>>k;
      |              ^~~
foo.cc:6:19: warning: unknown conversion type character 'k' in format [-Wformat=]
    6 |         printf("%.kf",a);
      |                   ^
foo.cc:6:16: warning: too many arguments for format [-Wformat-extra-args]
    6 |         printf("%.kf",a);
      |                ^~~~~~