#include <stdlib.h>
#include <stdio.h>
#include <stdbool.h>

// parse string into array of numbers
bool parse_numbers(char *str_row, unsigned long int *row, int len)
{
	int num = 0;
	for (int i = 0; str_row[i]; i++) {
		bool inced = false;
		while (str_row[i] < '0' || str_row[i] > '9') {
			if (str_row[i] == '\0')
				goto feck;
			if (!inced)
				num++;
			i++;
			inced = true;
		}
		// printf("assigning row[%d] = %lu when len=%d\n", num, row[num] * 10 + str_row[i] - '0', len);
		row[num] = row[num] * 10 + str_row[i] - '0';
	}
feck:

	return 1;
}

unsigned long int int_cat(unsigned long int a, unsigned long int b)
{
	unsigned long int bee = b;
	a *= 10;
	while ((bee /= 10) > 0) {
		a *= 10;
	}
	return a += b;
}

// power! x to the y!
int pow(int x, int y)
{
	int ans = 1;
	for (int i = 0; i < y; i++) ans *= x;
	return ans;
}
bool possible(unsigned long int *row, int len)
{
	// row[0] is the answer, len - 1 numbers, len - 2 operations
	//printf("answer: %d\n", row[0]);
	int variants = pow(4, len - 2);
	for (int i = 0; i < variants; i++) {
		unsigned long int sum = row[1];
		for (int j = 2; j < len; j++) {
			if ((i >> ((j - 2) * 2) & 3) == 0) {
				sum = int_cat(sum, row[j]);
			} else if ((i >> ((j - 2) * 2) & 3) == 1) {
				sum = sum * row[j];
			} else {
				sum = sum + row[j];
			}
		}
		// printf("sum: %d\n", sum);
		if (sum == row[0]) {
			// printf("sum %lu worked\n", sum);
			return 1;
		}
	}
	return 0;
}

int main()
{
	FILE *input;
	input = fopen("./input", "r");
	char line[100] = {0};
	unsigned long int sum = 0;
	while (fgets(line, sizeof(line), input)) {
		// count numonums, allocate array
		int numbers = 1;
		for (int c = 0; line[c]; c++) numbers += (line[c] == ' ');
		unsigned long int *row = calloc(numbers, sizeof(unsigned long int));
		parse_numbers(line, row, numbers);
		if (possible(row, numbers))
			sum = sum + row[0];
		free(row);
	}

	printf("sum: %llu\n", sum);
}