#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <string>
#include <cstdlib>
#include <queue>
#include <stack>
#include <cmath>
#include <vector>

#define ll long long
#define ull unsigned long long
#define lson l, m, rt<<1
#define rson m+1, r, rt<<1|1

using namespace std;


const int inf = 0x3f3f3f3f;
const int M = 75;
const int mod = 7;

int a[25], ans[25];

bool dfs(int i, int cnt){
    if(i == 0){
        int fff = 0;
        if(ans[i] == -1){
            if(a[i] > 7)
                return 0;
            else if(a[i] >4)
                ans[i] = 7;
            else{
                ans[i] = 4;
                fff = 1;
            }
        }
        int num = 0;
        for(int j = 0; j < cnt; j++){
            if(ans[j] == 4)
                num++;
        }
        if(fff && num == (cnt/2+1)){
            ans[i] = 7;
            num--;
        }
        if(num*2 == cnt)
            return 1;
        else{
            ans[i] = -1;
            return 0;
        }
    }
    if(a[i] < 4){
        int num = 0;
        for(int j = cnt-1; j > i; j--){
            if(a[j] == 4)
                num++;
        }
        for(int j = i; j >= 0; j--){
            if(num < cnt/2){
                ans[j] = 4;
                num++;
            }
            else
                ans[j] = 7;
        }
        if(dfs(0, cnt))
            return 1;
        else
            return 0;
    }
    if(a[i] > 7){
        ans[i] = -1;
        return 0;
    }
    if(a[i] == 7){
        ans[i] = 7;
        if(dfs(i-1, cnt))
            return 1;
        else
            return 0;
    }
    if(a[i] == 5 || a[i] == 6){
        ans[i] = 7;
        int num = 0;
        for(int j = cnt-1; j >= i; j--){
            if(ans[j] == 4)
                num++;
        }
        for(int j = i-1; j >= 0; j--){
            if(num < cnt/2){
                ans[j] = 4;
                num++;
            }
            else
                ans[j] = 7;
        }
        if(dfs(0, cnt))
            return 1;
        else
            return 0;
    }
    ans[i] = 4;
    if(dfs(i-1, cnt))
        return 1;
    else{
        ans[i] = 7;
        int num = 0;
        for(int j = cnt-1; j >= i; j--){
            if(ans[j] == 4)
                num++;
        }
        for(int j = i-1; j >= 0; j--){
            if(num < cnt/2){
                ans[j] = 4;
                num++;
            }
            else
                ans[j] = 7;
        }
        if(dfs(0, cnt))
            return 1;
        else
            return 0;
    }

}

int main()
{
    //freopen("input.txt", "r", stdin);

    int t;
    cin>>t;
    while(t--){
        ll n;
        scanf("%lld", &n);
        int cnt = 0;
        while(n){
            a[cnt++] = n%10;
            n /= 10;
        }
        int f = 0;
        if(cnt%2 == 0 && a[cnt-1] > 7){
            cnt += 2;
            f = 1;
        }

        if(cnt%2 || f){
            for(int i = 1; i <= (cnt+1)/2; i++)
                cout<<"4";
            for(int i = 1; i <= (cnt+1)/2; i++)
                cout<<"7";
            cout<<endl;
            continue;
        }
        else if(cnt == 0){
            cout<<"47"<<endl;
            continue;
        }
        memset(ans, -1, sizeof(ans));

        if(dfs(cnt-1, cnt)){
            for(int u = cnt-1; u >= 0; u--){
                cout<<ans[u];
            }
            cout<<endl;
        }
        else{
            cnt += 2;
            for(int i = 1; i <= cnt/2; i++)
                cout<<"4";
            for(int i = 1; i <= cnt/2; i++)
                cout<<"7";
            cout<<endl;
        }
    }

    return 0;
}