压根不用拼接，直接输出就行。

//C语言版代码
#include <stdio.h>
int main() {
    char s[100], t[100];
    while (scanf("%s%s", s, t) != EOF) {
        printf("%s%s\n", s, t);
    }
    return 0;
}
//C++版代码
#include <iostream>
using namespace std;
int main() {
    string s, t;
    while (cin >> s >> t) {
        cout << s << t << endl;
    }
    return 0;
}
//Java版代码
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            String s = sc.next();
            String t = sc.next();
            System.out.println(s + t);
        }
    }
}
#Python版代码
while True:
    try:
        print(input().replace(' ', ''))
    except:
        break