#include <stdio.h>
#include <string.h>
#include <ctype.h>

int main() {
    int n;
    if (scanf("%d", &n) != 1 || n < 1 || n > 1000) {
        printf("Invalid Input\n");
        return 0;
    }

    char arr[1001][101]; // max 1000 strings, each up to 100 chars

    for (int i = 0; i < n; i++) {
        if (scanf("%s", arr[i]) != 1) {
            printf("Invalid Input\n");
            return 0;
        }

        // Check if string contai
        for (int j = 0; arr[i][j] != '\0'; j++) {
            if (!isalpha(arr[i][j])) {
                printf("Invalid input\n");
                return 0;
            }
        }
    }
    for (int i = n - 1; i >= 0; i--) {
        printf("%s", arr[i]);
        if (i > 0) printf("");
    }
    printf("\n");

    return 0;
}