#include <stdio.h>
#include <ctype.h>

char findMinASCII(const char *str) {
    const char *ptr = str;
    char minChar = *ptr;

    while (*ptr) {
        if (isdigit(*ptr)) {
            return '\0'; // Signal invalid input
        }
        if (*ptr < minChar) {
            minChar = *ptr;
        }
        ptr++;
    }
    return minChar;
}

int main() {
    char input[100];
    printf(" ");