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

int main(){
	cin.tie(0),ios::sync_with_stdio(false);
	string s; cin>>s;
	vector<int>v(5,0);
	for(auto&&i:s)++v.at(i%8-3);
	auto sq=[](int a){return (uint64_t)a*a;};
	cout<<sqrtl(sq(abs(v.at(0)-v.at(3)))+sq(abs(v.at(2)-v.at(4))))<<"\n"s;
}