foo.cc: In function 'int main()':
foo.cc:12:16: warning: format '%d' expects argument of type 'int', but argument 2 has type 'double' [-Wformat=]
   12 |     printf("%.1d",sum);
      |             ~~~^  ~~~
      |                |  |
      |                |  double
      |                int
      |             %.1f

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