Compilare: main.cpp: In function 'int getcommon(int, int, std::vector<std::vector<int> >&)': main.cpp:30:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (x + (1 << i) > prefix[0].size() || y + (1 << i) > prefix[0].size()) ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~ main.cpp:30:55: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (x + (1 << i) > prefix[0].size() || y + (1 << i) > prefix[0].size()) ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:68:28: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen(iname, "r", stdin); ^ main.cpp:69:29: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen(oname, "w", stdout); ^ main.cpp:71:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] int T; scanf("%d", &T); ^ main.cpp:74:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] int N, K; scanf("%d%d\n", &N, &K); ^ main.cpp:76:29: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fgets(s, sizeof(s), stdin); ^