Compilare: main.cpp: In function 'void solve(int)': main.cpp:15:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < primes.size(); i++) { ~~^~~~~~~~~~~~~~~ main.cpp:30:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < f.size(); i++) ~~^~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:72:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sol.size(); i++) ~~^~~~~~~~~~~~ main.cpp:44:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("armonica.in", "r", stdin); ^ main.cpp:45:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("armonica.out", "w", stdout); ^