//#include <monsterenergy>
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const int MAX = 1e9;
const int MIN = -1*1e9;
const ll MAXLL = 1e18;
const ll MINLL = -1*1e18;

int main()
{
    string S; cin >> S;
    int c = 0;
    stack<char> Q;
    for(auto &x : S)
    {
        Q.push(x);
        if(x == '<') c++;
        if(x == '>')
        {
            if(c == 0) continue;
            Q.pop();
            if(Q.top() == '<')
            {
            	Q.push('>');
            	c = 0;
            	continue;
            }
            Q.push('>');
            while(Q.top() != '<') Q.pop();
            Q.pop();
            c--;
        }
    }
    cout << Q.size() << endl;
    return 0;
}