Compilare: main.cpp: In function 'int main()': main.cpp:59:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 59 | for(int i = 0; i < s1.size(); i ++) { | ~~^~~~~~~~~~~ main.cpp:65:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 65 | for(int i = 0; i < s2.size(); i ++) { | ~~^~~~~~~~~~~ main.cpp:71:22: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 71 | for(int i = 0; i < s3.size(); i ++) { | ~~^~~~~~~~~~~