foo.cc: In function 'int main()':
foo.cc:31:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   31 |  for(int i=0;i<v.size();i++)
      |              ~^~~~~~~~~
foo.cc: In function 'bool issushu(int)':
foo.cc:18:1: warning: control reaches end of non-void function [-Wreturn-type]
   18 | }
      | ^

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