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// q = 29, 101, 257, 65537, 100003, 1000033 (or random)
// m = 1500000001, 1600000009, 1700000009
// always compare hash and length of hashed range!
template<ll M, ll Q>
struct Hasher {
vector<ll> power = {1}, pref = {0};
Hasher(const string& s) {
for (auto x : s) {
power.push_back(power.back() * Q % M);
pref.push_back((pref.back() * Q % M + x) % M);
}}
ll hash(int l, int r) { // Berechnet hash(s[l..r)).
return (pref[r] - power[r-l] * pref[l] % M + M) % M;
}
};
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