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

int findMinDigit(int number, int min) {
    if (number < 10) {
        if(number < min) {
            return number;
        }
        else {
            return min;
        }
    }
    else {
        if((number % 10) < min) {
            findMinDigit(number/10, number%10);
        }
        else {
            findMinDigit(number/10, min);
        }
    }
}

int main() {
    int number;
    while (scanf("%d", &number)) {
        printf("%d\n", findMinDigit(number, 10000));
    }
    return 0;
}