Compilare: main.cpp: In function 'int main()': main.cpp:16:13: warning: unused variable 'j' [-Wunused-variable] int n,i,j; ^ main.cpp:9:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sum.in","r",stdin); ^ main.cpp:10:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sum.out","w",stdout); ^ main.cpp:17:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ main.cpp:21:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&a); ^