// CPP program to find the first
// repeated character in a string
#include <bits/stdc++.h>
using namespace std;
 
// Returns first repeating character in str.
char firstRepeating(string &str)
{
	// Creates an empty hashset
	unordered_set<char> h;
 
	// Traverse the input array from left to right
	for (int i=0; i<str.length(); i++)
	{
		char c = str[i];
 
		// If element is already in hash set, update x
		// and then break
		if (h.find(c) != h.end())
			return c;
 
		else // Else add element to hash set
			h.insert(c);
	}
 
	// If there was no repeated character
	return '\0';
}
 
// Driver method to test above method
int main ()
{
	string str ;
	int t;
	cin>>t;
	while(t--){
	getline(cin,str);
	cout << firstRepeating(str);}
	return 0;
}
 

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1
algorithms