Compilare: main.cpp: In function 'void read(int&, int&)': main.cpp:28:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0 ; i < s.size() ; i++) ~~^~~~~~~~~~ main.cpp:36:23: warning: statement has no effect [-Wunused-value] for(j ; j <= i ; j++) ^ main.cpp:39:23: warning: statement has no effect [-Wunused-value] for(j ; j <= i ; j++) ^ main.cpp: In function 'int main()': main.cpp:54:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ans.size() != n - 1){ ~~~~~~~~~~~^~~~~~~~