Compilare: user.cpp: In function ‘void build()’: user.cpp:75:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < nodes[i].size(); ++ j) ^ user.cpp: In function ‘int get()’: user.cpp:235:48: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf, 1, maxb, stdin), ptr = 0; ^ user.cpp:240:48: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf, 1, maxb, stdin), ptr = 0; ^ user.cpp: In function ‘int main()’: user.cpp:247:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("neapuiu.in", "r", stdin); ^ user.cpp:248:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("neapuiu.out", "w", stdout); ^ user.cpp:249:31: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buf, 1, maxb, stdin); ^