aaaaabb
 aabaaaa
 babbabaabbbbabwbvbhbbbaaabbabbbbbbbkabbbbabaaabbbbbbajabbaaabazbbbzbalbabbwbbaabbabacabdbabbbfaaabbb
 baaahbbbba
 ababavvvv
 abnxabbaab
 krflnzhter
 amaabbbbxaabbbabaabaabbaaabaaaaabibbabaabaaabaabcaaxabablbbbbmbbbaaaaaabbaabbbaaabaaaababaababbabbbb
 babbbaaaaaabbbaabaaaaaoaabababaababaaaaababaaaaaaabbbbbbaaapaabaaabaaababaaaabaaaabaaaaababaaaabaaab

5
 14
 42467327
 7
 7
 11
 0
 98718509
 813881762

#include <bits/stdc++.h>
#include <ext/hash_map>
#include <ext/numeric>

using namespace std;
using namespace __gnu_cxx;

#define REP(i,n) for( (i)=0 ; (i)<(n) ; (i)++ )
#define rep(i,x,n) for( (i)=(x) ; (i)<(n) ; (i)++ )
#define REV(i,n) for( (i)=(n) ; (i)>=0 ; (i)-- )
#define FORIT(it,x) for( (it)=(x).begin() ; (it)!=(x).end() ; (it)++ )
#define foreach(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();++it)
#define rforeach(it,c) for(__typeof((c).rbegin()) it=(c).rbegin();it!=(c).rend();++it)
#define foreach2d(i, j, v) foreach(i,v) foreach(j,*i)
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define SZ(x) ((int)(x).size())
#define MMS(x,n) memset(x,n,sizeof(x))
#define mms(x,n,s) memset(x,n,sizeof(x)*s)
#define pb push_back
#define mp make_pair
#define NX next_permutation
#define UN(x) sort(all(x)),x.erase(unique(all(x)),x.end())
#define CV(x,n) count(all(x),(n))
#define FIND(x,n) find(all(x),(n))-(x).begin()
#define ACC(x) accumulate(all(x),0)
#define PPC(x) __builtin_popcountll(x)
#define LZ(x) __builtin_clz(x)
#define TZ(x) __builtin_ctz(x)
#define mxe(x) *max_element(all(x))
#define mne(x) *min_element(all(x))
#define low(x,i) lower_bound(all(x),i)
#define upp(x,i) upper_bound(all(x),i)
#define NXPOW2(x) (1ll << ((int)log2(x)+1))
#define PR(x) cout << #x << " = " << (x) << endl ;

typedef unsigned long long ull;
typedef long long ll;
typedef vector<int> vi;
typedef vector<vector<int> > vvi;
typedef pair<int, int> pii;

const int OO = (int) 2e9;
const double eps = 1e-9;

const int mod = (int) 1e9 + 7;
const int N = 100005;

string s;
int n;
vi a, b;

int main() {
	std::ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	cout.tie(NULL);
#ifndef ONLINE_JUDGE
//	freopen("in.txt", "rt", stdin);
//	freopen("out.txt", "wt", stdout);
#endif
	cin >> s;
	n = SZ(s);
	ll res = 0;
	char prv = 'a';
	a.pb(0);
	for (int i = 0; i < n; i++) {
		if (s[i] == 'a') {
			if (prv == 'a')
				a.back()++;
			else
				a.pb(1);
			prv = 'a';
			res++;
		} else if (s[i] == 'b') {
			if (prv == 'a')
				b.pb(1);
			else
				b.back()++;
			prv = 'b';
		}
	}
	int m = SZ(b);
	if (prv == 'b')
		m--;
	ll pre = 0;
	for (int i = 0; i < m; i++) {
		int j = i + 1;
		(res += a[i] * 1LL * a[j] % mod) %= mod;
		(res += pre * a[i] % mod) %= mod;
		pre = res;
	}
	cout << res % mod << endl;
	return 0;
}
