Compilare: user.cpp: In function ‘int main()’: user.cpp:59:18: warning: unused variable ‘key’ [-Wunused-variable] for (int i = 1, key; i <= N; ++i){ ^ user.cpp:55:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("take5.in", "r", stdin); ^ user.cpp:56:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("take5.out", "w", stdout); ^ user.cpp: In function ‘int read_int()’: user.cpp:30:57: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] if (++bpos == DIM) fread(buf, 1, DIM, stdin), bpos = 0; ^