foo.cc:3:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
    3 | main()
      |      ^
foo.cc: In function 'int main()':
foo.cc:15:15: warning: format '%d' expects argument of type 'int', but argument 2 has type 'long int' [-Wformat=]
   15 |    printf("%-4d",i);
      |            ~~~^  ~
      |               |  |
      |               |  long int
      |               int
      |            %-4ld

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