#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int main() {
    int tt;
    scanf("%d", &tt);
    while (tt--) {
        char str[30], ans[30], ans1[30];
        scanf("%s", str);
        int len = strlen(str), flag = 0;
        int fo = 0, sev = 0, anslen = 0;
        if (str[0] > '7') {flag = 1; ans1[anslen++] = '4';}
        for (int i = 0; i < len; ++i) {
            if (flag == 1) {ans[i] = '4'; }
            else if(str[i] < '4'){ans[i] = '4';flag=1;}
            else if(str[i] == '4'){ans[i] = '4'; }
            else if (str[i] < '7') {ans[i] = '7'; if (str[i] < '7')flag = 1;}
            else if (str[i] == '7') {
                ans[i]=0;
                int j = i;
                while (j < len) {if (str[j] == '7') {j++;} else {if (str[j]>'7'){if (ans[i - 1] == '4') {
                    ans[i - 1] = '7';
                    flag = 1;
                    ans[i] = '4';
                    //printf("fdsa3\n");
                } else {
                    //printf("fdsa4\n");
                    ans1[anslen++] = '4'; flag = 1;
                    ans[i] = '4';
                }}else{ans[i]='7';}break;}}
                if(ans[i]==0)ans[i]='7';
            } else {
                if (ans[i - 1] == '4') {
                    ans[i - 1] = '7';
                    flag = 1;
                    ans[i] = '4';
                    //printf("fdsa3\n");
                } else {
                    //printf("fdsa4\n");
                    ans1[anslen++] = '4'; flag = 1;
                    ans[i] = '4';
                }
            }
            ans[i + 1] = '\0';
        }
        if ((len + anslen) % 2) {
            ans1[anslen++] = '4';
        }
        for (int i = 0; i < len; i++) {
            ans1[anslen++] = ans[i];
        }
        
        //printf("%s %s\n", ans1,ans);
        for (int i = 0; i < anslen; i++) {
            if (ans1[i] == '4')fo++;
            if (ans1[i] == '7')sev++;
        }
        if(sev>fo){
            ans1[anslen++] ='4';
        }
        if ( anslen % 2) {
            ans1[anslen++] = '4';
        }
        ans1[anslen] = '\0';
        //printf("fo%d sev%d\n", fo, sev );
        for (int i = anslen - 1; i > anslen - 1 - (fo - sev) / 2; i--) {
            ans1[i] = '7';
        }
        if (anslen > len)sort(ans1, ans1 + anslen);
        printf("%s\n", ans1);
    }

    return 0;
}