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 (GCC 5.4.1) (judge verdict: Accepted)

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main(void){
	char s[500001];
	int a[500000], b[500000];
	scanf("%s", s);
	int n=strnlen(s, 500000)+1, i;
	a[0]=0;
	for(i=0; i<=n-2; i++){
		if(s[i]=='<'){
			a[i+1] = a[i]+1;
		}else{
			a[i+1] = 0;
		}
	}
	b[n-1]=0;
	for(i=n-2; i>=0; i--){
		if(s[i]=='>'){
			b[i] = b[i+1]+1;
		}else{
			b[i] = 0;
		}
	}
	long sum=0;
	for(i=0; i<n; i++){
		sum+=a[i]<b[i]?b[i]:a[i];
	}
	printf("%ld\n", sum);
}