Compilare: main.cpp: In function 'int main()': main.cpp:51:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i>=len) hash = hash - p*(str[i-len]-'a'); ~^~~~~ main.cpp:52:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i>=len-1) ans += (int) Hash.contains(hash); ~^~~~~~~