Compilare: user.cpp: In function ‘int main()’: user.cpp:12:12: warning: unused variable ‘j’ [-Wunused-variable] int n, i, j; ^ user.cpp:20:6: warning: variable ‘s’ set but not used [-Wunused-but-set-variable] int s=a[1].a, d=a[1].b; ^ user.cpp:14:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("int.in", "r", stdin); ^ user.cpp:15:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("int.out", "w", stdout); ^ user.cpp:16:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:17:50: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i=1;i<=n;i++)scanf("%d%d", &a[i].a, &a[i].b); ^