Compilare: user.cpp: In function ‘int main()’: user.cpp:53:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hallway.in", "r", stdin); ^ user.cpp:54:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hallway.out", "w", stdout); ^ user.cpp:56:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &m, &n, &k); ^ user.cpp:57:52: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i=1; i<=k; ++i) scanf("%d%d", &y[i], &x[i]); ^