Compilare: main.cpp: In function 'void insert(it*&, long long int, char)': main.cpp:102:14: warning: unused variable 'n2' [-Wunused-variable] it *n1, *n2; ^~ main.cpp: In function 'int32_t main()': main.cpp:136:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<S.length(); i++){ ~^~~~~~~~~~~ main.cpp:144:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<L[i].length(); j++){ ~^~~~~~~~~~~~~~