Compilare: main.cpp: In function 'void back(int, long long int)': main.cpp:12:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos == primes.size()) ~~~~^~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:61:39: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<long long int>::size_type {aka long unsigned int}' [-Wformat=] printf("%d\n", divisors.size()); ^ main.cpp:73:39: warning: format '%d' expects argument of type 'int', but argument 2 has type 'std::vector<long long int>::size_type {aka long unsigned int}' [-Wformat=] printf("%d\n", divisors.size()); ^ main.cpp:53:39: 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:54:41: 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); ^ main.cpp:56:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^