Compilare: user.cpp: In function ‘void solve2()’: user.cpp:39:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < primes.size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:70:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nummst.in", "r", stdin); ^ user.cpp:71:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("nummst.out", "w", stdout); ^ user.cpp:73:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^