#include #define MOD 1000000007LL using namespace std; typedef long long ll; typedef pair P; ll mod_pow(ll x,ll n){ ll res=1; while(n>0){ if(n&1){ res=res*x%MOD; } x=x*x%MOD; n>>=1; } return res; } class segtree{ public: static const int N=1<<18; ll dp[1<<19]; segtree(){ memset(dp,0,sizeof(dp)); } void update(int k,ll v){ k+=N-1; dp[k]+=v; while(k>0){ k=(k-1)/2; dp[k]=(dp[k*2+1]+dp[k*2+2])%MOD; } } ll query(int a,int b,int k=0,int l=0,int r=N){ if(b<=l || r<=a)return 0; if(a<=l && r<=b)return dp[k]; int mid=(l+r)/2; ll vl=query(a,b,k*2+1,l,mid); ll vr=query(a,b,k*2+2,mid,r); return (vl+vr)%MOD; } }; string s; ll dp[200005]; ll sum[200005]; segtree seg[28]; int main(void){ cin >> s; int n=s.size(); ll ans=0; dp[0]=1; seg[26].update(0,1); for(int i=0;i