Compilare: main.cpp: In function 'int main()': main.cpp:30:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 30 | for(int i = 0; i < s1.size(); i ++) | ~~^~~~~~~~~~~ main.cpp:38:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 38 | for(int i = 0; i < s2.size(); i ++) | ~~^~~~~~~~~~~ main.cpp:46:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 46 | for(int i = 0; i < s3.size(); i ++) | ~~^~~~~~~~~~~