Compilare: main.cpp: In function 'int main()': main.cpp:24:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < pr.size() && i * pr[j] <= N && pr[j] <= currentLowestPrime; j++) { ~~^~~~~~~~~~~ main.cpp:11:32: 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:12:34: 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:14:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &N); ^