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 9.2.1) (judge verdict: Accepted)

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

int main()
{
	char S[500002];
	scanf("%s", S);
	
	int i = 0, j, up, down;
	long long sum = 0;
	while (S[i] != 0) {
		up = 0;
		down = 0;
		while (S[i] == '<') {
			up++;
			i++;
		}
		while (S[i] == '>') {
			down++;
			i++;
		}
		sum += (long long)up * (up - 1) / 2 + (long long)down * (down - 1) / 2 + ((up < down)? down: up);
	}
	
	printf("%lld\n", sum);
	fflush(stdout);
	return 0;
}