#include <iostream>
#include <cstring>
using namespace std;

int val(char c) {
    if (c >= '0' && c <= '9')
        return (int)c - '0';
    else
        return (int)c - 'A' + 10;
}
int toDeci(char *str, int base) {
    int len = strlen(str);
    int power = 1;
    int num = 0;
    int i;
    for (i = len - 1; i >= 0; i--) {
        if (val(str[i]) >= base) {
            printf("Invalid Number");
            exit(-1);
        }
        num += val(str[i]) * power;
        power = power * base;
    }
    return num;
}
char reVal(int num) {
    if (num >= 0 && num <= 9)
        return (char)(num + '0');
    else
        return (char)(num - 10 + 'A');
}
void strev(char *str) {
    int len = strlen(str);
    int i;
    for (i = 0; i < len/2; i++) {
        char temp = str[i];
        str[i] = str[len-i-1];
        str[len-i-1] = temp;
    }
}
char* fromDeci(char res[], int base, int inputNum) {
    int index = 0;
    while (inputNum > 0) {
        res[index++] = reVal(inputNum % base);
        inputNum /= base;
    }
    res[index] = '\0';
    strev(res);
    return res;
}
int main() {
    cout << "Vvedite chislo: ";
    char num1[256];
    cin >> num1;
    cout << "Vvedite staroe osnovanie: ";
    int num1b;
    cin >> num1b;
    int indec = toDeci(num1, num1b);
    cout << "Vvedite novoe osnovanie: ";
    int num2b;
    cin >> num2b;
    char res[128] = {0};
    char* num2 = fromDeci(res, num2b, indec);
    cout << "Converted: " << num2 << endl;
}