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

int sum_of_substrings(char *num) {
    int sum = 0;
    int len = strlen(num);
    for (int i = 0; i < len; i++) {
        int val = 0;
        for (int j = i; j < len; j++) {
            val = val * 10 + (num[j] - '0');
            sum += val;
        }
    }
    return sum;
}

int main() {
    char num[] = "1234";
    printf("Sum of all substrings of '%s': %d\n", num, sum_of_substrings(num));
    return 0;
}