Compilare: main.cpp: In function 'int main()': main.cpp:26:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < primes.size() and primes[i] <= b; ++i) { ~~^~~~~~~~~~~~~~~ main.cpp:39:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < primes.size() and v != 1; ++i) { ~~^~~~~~~~~~~~~~~ main.cpp:10:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("overpower.in", "r", stdin); ^ main.cpp:11:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("overpower.out", "w", stdout); ^