#include<stdio.h>

int main() {

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

    for (int i=0; i<n; i++){
        int x;
        scanf("%d", &x);
    // all ok above

        int arr[x];

        for (int k=1; k<=x; k++){
            arr[k-1] = k;
        }


        // even works fin - no touch
        for (int k=0; k+1<x; k+=2){
            int tem = arr[k];
            arr[k] = arr[k+1];
            arr[k+1] = tem;
        }

        // odd - 2 1 3 >> 2 3 1
        if (x%2!=0 && x >= 3){
            int tem2 = arr[x-1];
            arr[x-1] = arr[x-2];
            arr[x-2] = tem2;

        }


        // work below
        for (int fin=0; fin < x; fin++){
            printf("%d ", arr[fin]);
        }

    // prints new line
        printf("\n");
    }

}