진법 변환

#include <algorithm>
#include <iostream>
#include <stdio.h>
#include <vector>
#include <map>
#include <stack>
#include <queue>
#include <deque>
#include <string>
#include <cmath>
using namespace std;



int main() {
	//freopen("input.txt", "rt", stdin);
	string n;
	int b;
	cin >> n >> b;
	long long result = 0;
	int s = n.size()-1;
	for (int i = 0; i < n.size(); i++) {
		int tmp;
		//printf("%d\n", tmp);
		if (n[s] >= '0' && n[s] <= '9') {
			tmp = n[s] - '0';
		}
		if (n[s] >= 'A') {
			tmp = n[s] - 'A' + 10;
		}
		result = result + tmp * pow(b, i);
		s--;
	}
	printf("%lld", result);


	return 0;
}