Compilare: user.cpp: In function ‘int main()’: user.cpp:61:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ssnd.in", "r", stdin); ^ user.cpp:62:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ssnd.out", "w", stdout); ^ user.cpp:66:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld", &n); ^ user.cpp:72:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld", &u); ^ user.cpp: In function ‘void c()’: user.cpp:14:18: warning: iteration 1000000u invokes undefined behavior [-Waggressive-loop-optimizations] if(ciur[i] == 0) ^ user.cpp:12:19: note: containing loop for(int i=2; i<=1000002; i++) ^