Compilare: user.cpp: In function ‘void add_to_solve_1(const char*)’: user.cpp:23:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (maxim < strlen(s)) { ^ user.cpp:27:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if (maxim == strlen(s)) { ^ user.cpp: In function ‘bool verify(const char*)’: user.cpp:52:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < a.size(); ++i) { ^ user.cpp:65:63: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (letters[s[j] - 'a'] < a[i][s[j] - 'a'].size()) { ^ user.cpp: In function ‘bool verify_sol()’: user.cpp:107:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < solution.size(); ++i) { ^ user.cpp: In function ‘void print_solution2()’: user.cpp:135:40: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 3 has type ‘std::vector<std::basic_string<char> >::size_type {aka unsigned int}’ [-Wformat=] fprintf(g, "%lu\n", solution.size()); ^ user.cpp:136:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < original.size(); ++i) { ^ user.cpp:137:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < solution.size(); ++j) { ^ user.cpp: In function ‘int main(int, const char**)’: user.cpp:165:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < words.size(); ++i) { ^ user.cpp:147:33: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f, "%d %d\n", &V, &N); ^ user.cpp:149:32: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(str, STR_SIZE, f); ^