#include<bits/stdc++.h>
using namespace std;
const int M = 1e9 + 7;
int dp[200005], n;
int main(){
    string s;
    cin >> s;
    n = s.size();
    s.insert(0, " ");
    for(int i = 1; i <= n; i++){
        dp[i] = 1;
        for(int j = i - 1; j >= 1; j--){
            if(s[i] == s[j]) dp[i] = (dp[i] + dp[j]) % M;
            else dp[i] = (0LL + dp[i] + dp[j] * 2) % M;
        }
    }
    int ans = 0;
    // for(int i = 1; i <= n; i++) cout << dp[i] << " \n"[i == n];
    for(int i = 1; i <= n; i++) ans = (ans + dp[i]) % M;
    cout << ans;
    return 0;
}