foo.c: In function 'main':
foo.c:5:18: error: 'true' undeclared (first use in this function)
   for (int n = 1;true;n++) {
                  ^~~~
foo.c:5:18: note: each undeclared identifier is reported only once for each function it appears in
foo.c:8:18: error: expected expression before 'double'
       sum += 1.0/double(i);
                  ^~~~~~
foo.c:4:3: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d",&k);
   ^~~~~~~~~~~~~~

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