kasturba

#include <bits/stdc++.h>

using namespace std;

long multiply(long x, long y, int BASE = 10)
{
    const int xLength = to_string(x).length();
    const int yLength = to_string(y).length();

    int maxi = max(xLength, yLength);
    if (maxi < 10)
        return (long)x * (long)y;
    int N = maxi / 2;
    long multiplier = (long)pow(BASE, N);
    long a = x / multiplier;
    long b = x % multiplier;
    long c = y / multiplier;
    long d = y % multiplier;

    long ac = multiply(a, c, BASE);
    long bd = multiply(b, d, BASE);
    long res = multiply((a + b), (c + d), BASE);

    long result = ac * (long)pow(BASE, N) + bd + ((long)pow(BASE, N / 2) * res);
    return result;
}

int main()
{
    long x = 134, y = 2343434;

    cout << x << " times " << y << " = " << multiply(x, y) << endl;

    return 0;
}