Submission

Score: 100

User: goine

Problemset: ตัวอักษรตัวแรกในคำ

Language: cpp

Time: 0.002 second

Submitted On: 2025-10-12 11:58:22

#include<iostream>
#include<set>
using namespace std;

int main() {
    string x;
    cin >> x;

    char first = 'Z' + 1;
    set<char> d;

    for (char c : x) {
        if (d.find(c) == d.end()) d.emplace(c);
        else d.erase(c);
    }

    for (char c : d) {
        if (c < first) first = c;
    }

    if (first != 'Z' + 1)
	    cout << first;

    return 0;
}