//#include <bits/stdc++.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <iomanip>
#include <numeric>
#include <cmath>
#include <cstdint>
#include <stack>
#include <cassert>

#define rep(i,n) for(int i = 0; i < (n); i++) //[0,n)
#define srep(i,a,b) for(int i = (a); i < (b); i++) //[a,b)
#define all(A) (A).begin(),(A).end()
#define rall(A) (A).rbegin(),(A).rend()
using namespace std;
using ll = long long;
using ull = unsigned long long;
const ll inf = 1LL<<60;
const int iinf = (int)1e9+1;
const int mod9 = 998244353;
const int mod1 = (int)1e9+7;
struct Edge { int to; long long cost; int from; int i; };
bool compe(const Edge &e,const Edge &e2){ return e.cost < e2.cost; }
using Graph = vector<vector<int>>;
using EGraph = vector<Edge>;
using SGraph = vector<set<ll>>;
template <class T>
int siz(T& a){return (int)a.size();}
double square(double a){ return 1.0*a*a; }
double torad(double x){ return x*(acos(-1)/180.0); }
ll cross(ll ax,ll ay,ll bx,ll by){ return ax*by-ay*bx; }
ll mceil(ll a,ll b){ return (a+b-1)/b; }
using P = pair<ll,int>;

int main(){
    string S; cin >> S;
    int p = 0;

    stack<char> st;
    rep(i,siz(S)){
        st.push(S[i]);

        if(S[i] == '>') p--;
        if(S[i] == '>' && p >= 0){
            st.pop();

            if(siz(st) && st.top() != '='){
                st.push(S[i]);
                continue;
            }
            while(st.top() != '<') st.pop();
            st.pop();
        }
        else if(S[i] == '<') p++;
    }

    cout << siz(st);
}