Compilare: main.cpp: In function 'int main()': main.cpp:67:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 67 | for(int i=0;i<s1.length();i++) | ~^~~~~~~~~~~~ main.cpp:79:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 79 | for(int i=0;i<s2.length();i++) | ~^~~~~~~~~~~~ main.cpp:91:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 91 | for(int i=0;i<s3.length();i++) | ~^~~~~~~~~~~~