Compilare: user.cpp: In function ‘int main()’: user.cpp:5:11: warning: unused variable ‘first’ [-Wunused-variable] #define x first ^ user.cpp:50:18: note: in expansion of macro ‘x’ for (int i = 1, x; i <= n; i++) dist[i] = 1e9; ^ user.cpp:40:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("marmelada.in", "r", stdin); ^ user.cpp:41:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("marmelada.out", "w", stdout); ^