#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
inline void FFT (vector < complex <long double> >& sir , const bool invers)
{
const int lungime = (int)sir.size();
for (int indice = 1 , __indice = 0 ; indice < lungime ; indice++)
{
int putere = (lungime >> 1);
for ( ; __indice & putere ; putere >>= 1)
{ __indice ^= putere; }
if (indice < (__indice ^= putere))
{ swap(sir[indice] , sir[__indice]); }
}
for (int lungime_secventa = 2 ; lungime_secventa <= lungime ; lungime_secventa <<= 1)
{
const long double unghi = (invers ? -2 : 2) * M_PI / lungime_secventa;
const complex <long double> baza(cos(unghi) , sin(unghi));
for (int inceput = 0 ; inceput < lungime ; inceput += lungime_secventa)
{
complex <long double> putere = 1;
for (int indice_1 = inceput , indice_2 = inceput + (lungime_secventa >> 1) ; indice_2 < inceput + lungime_secventa ; indice_1++ , indice_2++)
{
const complex <long double> factor_1 = sir[indice_1];
const complex <long double> factor_2 = putere * sir[indice_2];
sir[indice_1] = factor_1 + factor_2;
sir[indice_2] = factor_1 - factor_2;
putere *= baza;
}
}
}
if (invers) {
for (auto& valoare : sir)
{ valoare /= lungime; }
}
}
inline void Inmultire (vector <int>& factor_1 , vector <int>& factor_2)
{
int lungime = 1;
while (lungime < (int)factor_1.size() + (int)factor_2.size())
{ lungime <<= 1; }
vector < complex <long double> > __factor_1(lungime);
for (int indice = 0 ; indice < (int)factor_1.size() ; indice++)
{ __factor_1[indice] = factor_1[indice]; }
vector < complex <long double> > __factor_2(lungime);
for (int indice = 0 ; indice < (int)factor_2.size() ; indice++)
{ __factor_2[indice] = factor_2[indice]; }
FFT(__factor_1 , false);
FFT(__factor_2 , false);
for (int indice = 0 ; indice < lungime ; indice++)
{ __factor_1[indice] *= __factor_2[indice]; }
FFT(__factor_1 , true);
int transport = 0;
factor_1.resize(lungime);
for (int indice = 0 ; indice < lungime ; indice++ , transport /= 10)
{ factor_1[indice] = (transport += (int)round(__factor_1[indice].real())) % 10; }
for ( ; transport ; transport /= 10)
{ factor_1.push_back(transport % 10); }
while ((int)factor_1.size() > 1 && !factor_1.back())
{ factor_1.pop_back(); }
}
char sir_1[100001] , sir_2[50001];
int main ()
{
ios :: sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
int lungime_1 , lungime_2;
cin >> lungime_1 >> lungime_2 >> sir_1 >> sir_2;
vector <int> factor_1(lungime_1) , factor_2(lungime_2);
for (int indice = 0 ; indice < lungime_1 ; indice++)
{ factor_1[indice] = sir_1[lungime_1 - 1 - indice] - '0'; }
for (int indice = 0 ; indice < lungime_2 ; indice++)
{ factor_2[indice] = sir_2[lungime_2 - 1 - indice] - '0'; }
Inmultire(factor_1 , factor_2);
for (int indice = 0 ; indice < (int)factor_1.size() ; indice++)
{ sir_1[(int)factor_1.size() - 1 - indice] = factor_1[indice] + '0'; }
cout.write(sir_1 , factor_1.size());
return 0;
}
