Compilare: main.cpp: In function 'int read_int(int&)': main.cpp:22:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 22 | for (; poz < s.size() and s[poz] >= '0' and s[poz] <= '9'; poz++) | ~~~~^~~~~~~~~~ main.cpp: In function 'bool checker(int)': main.cpp:34:16: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 34 | for (; poz < s.size() and s[poz] != '+'; poz++) | ~~~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:53:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 53 | while (poz < s.size()) | ~~~~^~~~~~~~~~