#include <stdio.h>
int main() {
    int n,a[100];
    scanf("%d",&n);
    if(n < 1 ||n > 100) {printf("Invalid");return 0;}
    for(int i = 0; i<n; i++)
    if (scanf("%d",&a[i])!=1){print("Invalid");return 0;}
    
    for(int i = 0;i < n - 1;i +=2){
        int t =a[i];a[i] = a[i+1];a[i+1]=t;
    }
    for(int i =0;i<n;i++)printf("%d",a[i]);
    return 0;
    }