Compilare: main.cpp: In function 'void Solve()': main.cpp:55:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(S.size()<k) ~~~~~~~~^~ main.cpp:58:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<S.size(); i++) ~^~~~~~~~~ main.cpp:42:11: warning: unused variable 'j' [-Wunused-variable] int i,j; ^