Compilare: main.cpp: In function 'int main()': main.cpp:16:18: warning: statement has no effect [-Wunused-value] for(j; j <= n; j += i) ^ main.cpp:6:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ciur.in", "r", stdin); ^ main.cpp:7:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("ciur.out", "w", stdout); ^ main.cpp:8:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^