【CodeForces - 1084C】The Fair Nut and String（思维，组合数学）

题干：

The Fair Nut found a string ss. The string consists of lowercase Latin letters. The Nut is a curious guy, so he wants to find the number of strictly increasing sequences p1,p2,…,pkp1,p2,…,pk, such that:

For each ii (1≤i≤k1≤i≤k), spi=spi= 'a'.
For each ii (1≤i<k1≤i<k), there is such jj that pi<j<pi+1pi<j<pi+1 and sj=sj= 'b'.

The Nut is upset because he doesn't know how to find the number. Help him.

This number should be calculated modulo 109+7109+7.

Input

The first line contains the string ss (1≤|s|≤1051≤|s|≤105) consisting of lowercase Latin letters.

Output

In a single line print the answer to the problem — the number of such sequences p1,p2,…,pkp1,p2,…,pk modulo 109+7109+7.

Examples

Input

abbaa

Output

Input

baaaa

Output

Input

agaa

Output

Note

In the first example, there are 55 possible sequences. [1][1], [4][4], [5][5], [1,4][1,4], [1,5][1,5].

In the second example, there are 44 possible sequences. [2][2], [3][3], [4][4], [5][5].

In the third example, there are 33 possible sequences. [1][1], [3][3], [4][4].

题目大意：

让你构造一个序列，有两个要求：1.全为‘a’字符。2.每两个a字符之间一定夹着至少一个b字符，求能构造出多少个这样的序列

解题报告：

扫一遍遇到a就记录，遇到b就终止并开始计数最后输出答案，就行了

AC代码：

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<queue>
#include<map>
#include<vector>
#include<set>
#include<string>
#include<cmath>
#include<cstring>
#define ll long long
#define pb push_back
#define pm make_pair
#define fi first
#define se second
using namespace std;
const int MAX = 2e5 + 5;
const ll mod = 1e9+7;
char s[MAX];
int main()
{scanf("%s", s + 1);int len = strlen(s + 1);ll ans = 1;for(int i = 1; i<=len; i++){ll cnt = 0;int cur = i;while(cur <= len){if(s[cur] == 'a') cnt++,cur++;else if(s[cur] == 'b') break;else cur++;}i = cur;ans = ans*(cnt+1) % mod;}ans--;printf("%lld\n", ans);return 0;}

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