#include <stdio.h>
#include <string.h>
#include <math.h>

int isFair(long long num) {
    char digits[20];
    sprintf(digits, "%lld", num);
    int evenCount = 0;
    int len = strlen(digits);
    for (int i = 0; i < len; i++) {
        if ((digits[i] - '0') % 2 == 0) evenCount++;
    }
    return evenCount == len - evenCount;
}

long long constructFair(int length) {
    if (length % 2 == 1) length++;
    int half = length / 2;
    char result[20] = {0};
    for (int i = 0; i < half; i++) result[i] = '1';
    for (int i = half; i < length; i++) result[i] = '0';
    return atoll(result);
}

long long nextBeautifulInteger(int n) {
    if (isFair(n)) return n;
    
    long long current = n + 1LL;
    char temp[20];
    sprintf(temp, "%d", n);
    long long limit = fmin(n * 2LL, (long long)pow(10, strlen(temp) + 1));
    
    while (current < limit) {
        if (isFair(current)) return current;
        current++;
    }
    
    sprintf(temp, "%d", n);
    return constructFair(strlen(temp));
}

int main() {
    int n;
    scanf("%d", &n);
    printf("%lld\n", nextBeautifulInteger(n));
    return 0;
}