Compilare: user.cpp: In function ‘int main()’: user.cpp:9:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.in", "r", stdin); ^ user.cpp:10:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.out", "w", stdout); ^ user.cpp:13:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:18:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &X, &Y); ^ user.cpp:41:18: warning: ‘ans’ may be used uninitialized in this function [-Wmaybe-uninitialized] ans+=k*(k-1)/2; ^