Compilare: main.cpp: In function 'void preproc()': main.cpp:17:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < S.size(); ++i) ~~^~~~~~~~~~ main.cpp: In function 'void solve()': main.cpp:42:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(K == S.size()) ~~^~~~~~~~~~~