Compilare: user.cpp: In function ‘int main()’: user.cpp:2:63: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int main(){freopen("adunare.in","r",stdin);freopen("adunare.out","w",stdout);int a,b;scanf("%d%d",&a,&b);printf("%d",a+b);} ^ user.cpp:2:97: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int main(){freopen("adunare.in","r",stdin);freopen("adunare.out","w",stdout);int a,b;scanf("%d%d",&a,&b);printf("%d",a+b);} ^ user.cpp:2:125: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] using namespace std;int main(){freopen("adunare.in","r",stdin);freopen("adunare.out","w",stdout);int a,b;scanf("%d%d",&a,&b);printf("%d",a+b);} ^