Compilare: user.cpp: In function ‘int main()’: user.cpp:56:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<prime_extra.size();i++){ ^ user.cpp:74:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<prime_extra.size();i++){ ^ user.cpp:28:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("exp.in", "r", stdin); ^ user.cpp:29:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("exp.out", "w", stdout); ^ user.cpp:31:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &m, &n); ^ user.cpp:35:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &a); ^