#include <stdio.h>
#include <algorithm>
#include <iostream>
#include <map>
#include <stack>
#include <vector>
#include <memory.h>
#include <set>
#include <string.h>
#include <list>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <queue>
#include <time.h>
#define ll long long
#define forn(i,n) for(int i=0;i<n;++i)
#define rep(i,n) for(int i=1;i<=n;++i)
#define repc(i,l,r) for(int i=l;i<=r;++i)
#define mp(a,b) make_pair(a,b)
#define llf long double
#define pii pair<int,int>
using namespace std;
void solve(){
    char s[20];
    char res[20];
    scanf("%s", s);
    int len = strlen(s);
    if (len % 2){
        forn(i, len / 2 + 1)printf("4");
        forn(i, len / 2 + 1)printf("7");
        printf("\n");
        return;
    }
    for (int i = 0; i < len / 2; ++i)res[i] = '7';
    for (int i = len / 2; i < len; ++i)res[i] = '4';
    res[len] = 0;
    if (strcmp(res, s) < 0){
        forn(i, len / 2 + 1)printf("4");
        forn(i, len / 2 + 1)printf("7");
        printf("\n");
        return;
    }
    int k = 0;
    int c4 = len / 2, c7 = len / 2;
    forn(i, len){
        if (c4){
            int _c4 = c4, _c7 = c7;
            res[i] = '4';
            --_c4;
            for (int j = i + 1; j < len; ++j){
                if (_c7){
                    --_c7;
                    res[j] = '7';
                }
                else{
                    --_c4;
                    res[j] = '4';
                }
            }
            if (strcmp(res, s) >= 0){
                --c4;
            }
            else{
                --c7;
                res[i] = '7';
            }
        }
        else{
            res[i] = '7';
        }
    }
    printf("%s\n", res);
}
int main(){
    //freopen("abc.txt", "r", stdin);
    int T;
    cin >> T;
    while (T--)
        solve();
    return 0;
}