Compilare: main.cpp: In function 'void read()': main.cpp:25:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pairs.in", "r", stdin); ^ main.cpp:26:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%lld", &n); ^ main.cpp:29:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%lld", &x); ^ main.cpp: In function 'void write()': main.cpp:45:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pairs.out", "w", stdout); ^