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

void Substr(char* str, int str_len) {
    int len_str_str = 0;
    char *i, *j;
    j = NULL;
    char* new_str = (char*)malloc(sizeof(char));

    for (i = str; i < str + str_len; i++) {
        if (isdigit(*i)) {
            *(new_str + len_str_str) = *i;
            new_str = (char*)realloc(new_str, (1 + (len_str_str++)) * sizeof(char));
        }

        if ((i != str) && (!isdigit(*i)) && (isdigit(*(i - 1)))) {
            *(new_str + len_str_str) = ' ';
            new_str = (char*)realloc(new_str, (1 + (len_str_str++)) * sizeof(char));
        }
    }
    *(new_str + len_str_str) = '\0';

    int len = 0, min_len = len_str_str;
    for (i = strtok(new_str, " "); i != NULL; i = strtok(NULL, " ")) {
        if (strlen(i) < min_len) {
            min_len = strlen(i);
            j = i;
        }
    }
    for (i = j; i < j + min_len; i++) {
        printf("%s", i);
    }
}

int main() {

    int str_len = 0;
    char ch;
    char* str = (char*)malloc(sizeof(char));

    //Введение строки
    printf("Enter string:\n");
    while ((ch = getchar()) != '\n') {
        *(str + str_len) = ch;
        str = (char*)realloc(str, (1 + (str_len++)) * sizeof(char));
    }
    *(str + str_len) = '\0';

    Substr(str, str_len);

    return 0;
}