typedef unsigned long long ull;
ull seed = 137;
ull bkdr_hash(){ 
	int len = s.length();
	ull ans = 0;
	for (int i = 0;i < s.length();i++)
		ans = ans * seed + s[i];
    return ans;
}

#include <bits/stdc++.h>
using namespace std;
typedef unsigned long long ull;
ull seed = 137;
string s;
ull bkdr_hash(){
	int len = s.length();
	ull ans = 0;
	for (int i = 0;i < s.length();i++)
		ans = ans * seed + s[i];
    return ans;
}
int main(){
    srand((unsigned)time(NULL));
    int tot = 1e5;
    set<ull> ss;
    ss.clear();
    for(int i=0; i<tot; i++){
        s.clear();
        int len = rand()%100;
        for(int j=0; j<len; j++){
            s += (rand()%26+'a');
        }
        ull hash_value = bkdr_hash();
        if(ss.count(hash_value)==0){
            ss.insert(hash_value);
        }
        else{
            cout<<"the insert number"<<i<<endl;
            printf("hash collision\n");
            break;
        }
    }
    return 0;
}