#include <stdio.h>

int main() {
    int n;
    
    if(scanf("%d" , &n)! =1 || n < 0) {
        printf("Invalid inpur");
        return 0;
    }
    int arr[n];
    
    for(int i = 0; i < n; i++) {
        if(scanf("%d", &arr[i])! = 1) {
            printf("Invalid input");
            return 0;
        }
    }
    for (int i = 0; i < n; i+=2) {
        printf("%d",arr[i]);
    }
    for (int i = 1; i < n; i+=2) {
        printf("%d",arr[i]);
}
return 0;
}