itoj

#include <iostream>

using namespace std;

int ans[100000], h;

void umn(int a, int base)
{
    int c = 0, t;
    for (int i = 0; i < h || c; i++)
    {
        if (i >= h) h++;
        t = ans[i] * a + c;
        ans[i] = t % base;
        c = t / base;
    }
}

void pls(int a, int base)
{
    int c = 0, t;
    if (!h) h++;
    ans[0] += a;
    for (int i = 0; i < h || c; i++)
    {
        if (i >= h) h++;
        t = ans[i] + c;
        c = t / base;
        ans[i] = t % base;
    }
}

int main()
{
    int bases, basef;
    char i;
    cin >> bases >> basef >> i;
    for (;;)
    {
        pls(((i > '9') ? i - 'A' + 10 : i - '0'), basef);
        if (cin >> i) umn(bases, basef);
        else break;
    }
    for (int i = h - 1; i > -1; i--)
        cout << (char)((ans[i] > 9) ? ans[i] - 10 + 'A' : ans[i] + '0');
    return 0;
}