//Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23506 for x64
#include
using namespace std;
int main()
{
size_t number = 0U, counter = 0U;
cin >> number;
for (size_t tmp = number % 10; number; tmp & 1 ? ++counter : 0,
number /= 10, tmp = number % 10);
cout << counter;<br>}