foo.cc: In function 'int main()':
foo.cc:49:24: warning: 's' is used uninitialized in this function [-Wuninitialized]
   49 |   for (ss* s = Head; s != NULL; s = s->next)
      |                        ^
foo.cc:61:5: note: 's' was declared here
   61 |  su s(n);
      |     ^

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