Compilare: user.cpp: In function ‘void read_data()’: user.cpp:22:7: warning: unused variable ‘s’ [-Wunused-variable] char s[MAXL]; ^ user.cpp:19:25: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(IN, "r", stdin); ^ user.cpp:20:27: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen(OUT, "w", stdout); ^ user.cpp:21:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &T); ^ user.cpp:32:20: warning: ‘buf[1]’ may be used uninitialized in this function [-Wmaybe-uninitialized] int num = buf[1] - '0'; ^