foo.cc: In function 'int main()':
foo.cc:27:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    if(pos.size()>ptr+1)
       ~~~~~~~~~~^~~~~~
foo.cc:11:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%s",s+1);
  ~~~~~^~~~~~~~~~

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