Compilare: main.cpp: In function 'int main()': main.cpp:42:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 1; j <= (S.size() - 1) / 2; j++ ){ ~~^~~~~~~~~~~~~~~~~~~~~ main.cpp:52:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 0; j < Sol[i].size(); j++ ) ~~^~~~~~~~~~~~~~~