foo.cc: In function 'int main()':
foo.cc:11:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   11 |  for (i = 0; i < s.size(); i++)
      |              ~~^~~~~~~~~~
foo.cc:19:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   19 |  for (i++; i < s.size(); i++)
      |            ~~^~~~~~~~~~
foo.cc:7:24: warning: unused variable 'b' [-Wunused-variable]
    7 |  int n, i, ans = 0, a, b;
      |                        ^
foo.cc:23:10: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]
   23 |    if (i - a == 1)
      |        ~~^~~

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