foo.cc: In function 'int main()':
foo.cc:9:2: error: 'cin' was not declared in this scope
    9 |  cin >> str;
      |  ^~~
foo.cc:5:1: note: 'std::cin' is defined in header '<iostream>'; did you forget to '#include <iostream>'?
    4 | #include<sstream>
  +++ |+#include <iostream>
    5 | using namespace std;

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