#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; typedef long long ll; typedef unsigned int ui; const ll mod = 1000000007; const ll INF = (ll)1000000007 * 1000000007; typedef pair P; #define stop char nyaa;cin>>nyaa; #define rep(i,n) for(int i=0;i=0;i--) #define Rep(i,sta,n) for(int i=sta;i=sta;i--) #define rep1(i,n) for(int i=1;i<=n;i++) #define per1(i,n) for(int i=n;i>=1;i--) #define Rep1(i,sta,n) for(int i=sta;i<=n;i++) typedef long double ld; const ld eps = 1e-8; const ld pi = acos(-1.0); typedef pair LP; int dx[4]={1,-1,0,0}; int dy[4]={0,0,1,-1}; template struct ModInt { long long x; ModInt() : x(0) {} ModInt(long long y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {} explicit operator int() const {return x;} ModInt &operator+=(const ModInt &p) { if((x += p.x) >= mod) x -= mod; return *this; } ModInt &operator-=(const ModInt &p) { if((x += mod - p.x) >= mod) x -= mod; return *this; } ModInt &operator*=(const ModInt &p) { x = (int)(1LL * x * p.x % mod); return *this; } ModInt &operator/=(const ModInt &p) { *this *= p.inverse(); return *this; } ModInt operator-() const { return ModInt(-x); } ModInt operator+(const ModInt &p) const { return ModInt(*this) += p; } ModInt operator-(const ModInt &p) const { return ModInt(*this) -= p; } ModInt operator*(const ModInt &p) const { return ModInt(*this) *= p; } ModInt operator/(const ModInt &p) const { return ModInt(*this) /= p; } bool operator==(const ModInt &p) const { return x == p.x; } bool operator!=(const ModInt &p) const { return x != p.x; } ModInt inverse() const{ int a = x, b = mod, u = 1, v = 0, t; while(b > 0) { t = a / b; a -= t * b; swap(a, b); u -= t * v; swap(u, v); } return ModInt(u); } ModInt power(long long p) const{ int a = x; if (p==0) return 1; if (p==1) return ModInt(a); if (p%2==1) return (ModInt(a)*ModInt(a)).power(p/2)*ModInt(a); else return (ModInt(a)*ModInt(a)).power(p/2); } ModInt power(const ModInt p) const{ return ((ModInt)x).power(p.x); } friend ostream &operator<<(ostream &os, const ModInt &p) { return os << p.x; } friend istream &operator>>(istream &is, ModInt &a) { long long x; is >> x; a = ModInt(x); return (is); } }; using modint = ModInt; int n; string s; modint po[200010]; modint f(vector &v){ int m=v.size()-1; modint S=0,res=0; Rep(i,1,m+1){ if(i>=2)S+=po[v[i-1]-1]; //cout << i << " " << v[i] << " " << S << " " << po[n-1]-po[n-i]-po[n-v[i]]*S+po[n-i] << endl; res+=po[n-1]-po[n-i]-po[n-v[i]]*S+po[n-i]; } return res; } void solve(){ cin >> s; n=s.length(); po[0]=1; rep(i,n){ po[i+1]=(modint)2*po[i]; } modint ans=0; rep(k,26){ vector v={0}; rep(i,n){ if(s[i]-'a'==k) v.push_back(i+1); } ans+=f(v); } cout << ans << endl; } int main(){ ios::sync_with_stdio(false); cin.tie(0); cout << fixed << setprecision(50); solve(); }