Problem:
Score : 300 points

Problem Statement

Given is a string S of length N-1.
Each character in S is < or >.

A sequence of N non-negative integers, a_1,a_2,\cdots,a_N, is said to be good when the following condition is satisfied for all i (1 \leq i \leq N-1):

If S_i= <: a_i<a_{i+1}

If S_i= >: a_i>a_{i+1}

Find the minimum possible sum of the elements of a good sequence of N non-negative integers.

Constraints

2 \leq N \leq 5 \times 10^5

S is a string of length N-1 consisting of < and >.

Input

Input is given from Standard Input in the following format:

S

Output

Find the minimum possible sum of the elements of a good sequence of N non-negative integers.

Sample Input 1

<>>

Sample Output 1

3

a=(0,2,1,0) is a good sequence whose sum is 3.
There is no good sequence whose sum is less than 3.

Sample Input 2

<>>><<><<<<<>>><

Sample Output 2

28

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

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

const int N = 5e5+10;
char a[N];

int32_t main(){
    cin>>a;
    //cout<<a<<endl;
    int len = strlen(a);
    int sum1 = 0, sum2 = 0;
    int ans = 0;
    bool f=0;
    if(a[len-1]=='>') a[len]='<';
    if(a[len-1]=='<') a[len]='>';
    for(int i = 0; i <= len; i++){
        if(a[i]=='<'){
            if(sum2){
                if(sum2 > sum1){
                    ans += (1+sum2)*sum2/2;
                    sum2=0;
                    sum1=0;
                }else{
                    ans += (1+sum2-1)*(sum2-1)/2;
                    ans += sum1;
                    sum2=0;
                    sum1=0;
                }
                f=0;
            }
            sum1++;
        }else{
            if(!f){
                ans += (1+sum1-1)*(sum1-1)/2;
                f=1;
            }
            sum2++;
        }
    }
    if(a[len]=='<')cout<<ans;
    else cout<<ans+sum1;
    return 0;
}