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<stdio.h>
#include<string.h>
#define chmax(p,q)(p<(q)?p=(q),1:0)
char s[500010];
int a[500010];
int main(){
	scanf("%s",s);
	int n=strlen(s);
	long long ans=0;
	for(int i=0;i<n;i++)if(s[i  ]=='<')chmax(a[i+1],a[i]+1);
	for(int i=n;i>0;i--)if(s[i-1]=='>')chmax(a[i-1],a[i]+1);
	for(int i=0;i<=n;i++)ans+=a[i];
	printf("%lld",ans);
}