Compilare: main.cpp: In function 'int read()': main.cpp:18:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ main.cpp:13:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^ main.cpp:15:31: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &a, &b); ^ main.cpp: In function 'int main()': main.cpp:26:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("reactivi.in", "r", stdin); ^ main.cpp:27:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("reactivi.out", "w", stdout); ^