foo.cc: In function 'int su(int)':
foo.cc:11:6: warning: unused variable 'n' [-Wunused-variable]
   11 |  int n/*,k=0*/;
      |      ^
foo.cc: In function 'int main()':
foo.cc:45:16: warning: format '%ld' expects argument of type 'long int', but argument 2 has type 'int' [-Wformat=]
   45 |    printf("%-4ld",i);
      |            ~~~~^  ~
      |                |  |
      |                |  int
      |                long int
      |            %-4d

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