#include <bits/stdc++.h>
using namespace std;

int main()
{
    string s;
    cin >> s;
    double t = 1, cnt = 0, len = s.size();
    if (s.front() == '-') t *= 1.5, len--;
    if ((s.back() - '0')% 2 == 0)  t *= 2;
    for (auto c : s)
        if (c == '2') cnt++;

    printf("%.2lf%%", cnt / len * t * 100);

    return 0;
}