task

z.c

#include <stdio.h>
#include <limits.h>

int upOrder(int n) {
    int k;
    int f = n % 10;

    n /= 10;
    while (n > 0) {
        k = n % 10;
        if (k < f) return 0;
        f = k;
        n /= 10;
    }
    return 1;
}

int downOrder(int n) {
    int k;
    int f = n % 10;

    n /= 10;
    while (n > 0) {
        k = n % 10;
        if (k > f) return 0;
        f = k;
        n /= 10;
    }
    return 1;
}

int main() {
    int num;
    int i;
    int max = INT_MIN;

    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);

    while (scanf("%d", &num) > 0)
        if (upOrder(num) || downOrder(num)) if (num > max) max = num;

    if (max == INT_MIN) printf("0");
    else printf("%d", max);

    return 0;    
}