foo.cc: In function ‘int main()’:
foo.cc:5:2: error: ‘cin’ was not declared in this scope
    5 |  cin>>a>>a>>c;
      |  ^~~
foo.cc:2:1: note: ‘std::cin’ is defined in header ‘<iostream>’; this is probably fixable by adding ‘#include <iostream>’
    1 | #include <stdio.h>
  +++ |+#include <iostream>
    2 | using namespace std;