// https://dashoj.com/p/96
#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

string s;
int base, power = 0;
ll result = 0;

int main() {
	cin >> s >> base;
	for (int i = s.size() - 1; i >= 0; i--) {
		int value;
		if (isdigit(s[i])) value = s[i] - '0';
		else value = s[i] - 'A' + 10;
		result += value * pow(base, power);
		power++;
	}
	cout << result << endl;
	return 0;
}