Compilare: user.cpp: In function ‘void solve()’: user.cpp:14:9: warning: unused variable ‘i’ [-Wunused-variable] int i, x = 0; ^ user.cpp: In function ‘void read()’: user.cpp:8:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("euler.in", "r", stdin); ^ user.cpp:9:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp: In function ‘void write()’: user.cpp:52:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("euler.out", "w", stdout); ^