Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:25:5: error: ‘aria’ was not declared in this scope aria += x1 * y2 - x2 * y1; ^~~~ user.cpp:5:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("aria.in", "r", stdin); ^ user.cpp:6:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("aria.out", "w", stdout); ^ user.cpp:10:45: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int N; scanf("%d %Lf %Lf", &N, &x0, &y0); ^ user.cpp:16:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%Lf %Lf", &x2, &y2); ^