Compilare: user.cpp: In function ‘int leading_zeroes(const string&)’: user.cpp:142:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < repr.size() && repr[i] == '0') ^ user.cpp:144:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (i == repr.size()) ^ user.cpp: In function ‘std::string base_10_representation(BigNum, int, int)’: user.cpp:164:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (after_decimal.size() > wanted_digits_after_decimal) ^ user.cpp: In function ‘int main()’: user.cpp:212:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sqrt.in", "r", stdin); ^ user.cpp:213:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sqrt.out", "w", stdout); ^