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

struct g {
    char name[100];
    struct g *tail;
};

int isValidName(char name[]) {
    for (int i = 0; name[i] != '\0'; i++) {
        if (!isalnum(name[i]))
            return 0;
    }
    return 1;
}

int main() {
    int n;
    scanf("%d", &n);

    struct g k[100]; 
    for (int i = 0; i < n; i++) {
        scanf("%s", k[i].name);
        if (!isValidName(k[i].name)) {
            printf("Invalid input\n");
            return 0;
        }
        if (i < n - 1)
            vi[i].tail = &visitors[i + 1];
        else
            visitors[i].tail = NULL;
    }

    struct Visitor *ptr = &visitors[0];
    while (ptr != NULL) {
        printf("%s", ptr->name);
        if (ptr->tail != NULL) printf(" ");
        ptr = ptr->tail;
    }

    return 0;
}