#include<stdio.h>

int main() {
    int n;
    scanf("%d", &n);
    if(n<0 || n>100){
        printf("-1");
        return 0;
    }
    int arr[n];
    int *p=arr;
    for(int i=0;i<n;i++){
        scanf("%d",(p+i));
    }
    int start=0,end=1;
    while(end < n) {
        int temp = *(p+start);
        (p+start) = (p+end);
        *(p+end)=temp;
         start=start+2;
          end=end+2;
    }
    for(int i=0;i<n;i++){
        printf("%d",*(p+i));
    }
}