#include <bits/stdc++.h>   const int mod = 998244353;   using namespace std;   long long gcd(long long a, long long b) {     if (a == 0) return b;     return gcd(b % a, a);   }   long long lcm(long long a, long long b) { return (a * b) / gcd(a, b); }   long long power(long long x, long long y) {     long long res = 1;     while (y > 0) {       if (y & 1) res = res * x;       y = y >> 1;       x = x * x;     }     return res;   }   long long pwr(long long a, long long b) {     if (b == 0) {       return 1;     }     long long p = pwr(a, b / 2);     p = (p * p) % mod;     if (b % 2 != 0) {       p = (p * a) % mod;     }     return p;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     long long n, m;     cin >> n >> m;     string a, b;     cin >> a >> b;     reverse(a.begin(), a.end());     reverse(b.begin(), b.end());     while (m > n) {       a +=  0 ;       n++;     }     while (n > m) {       b +=  0 ;       m++;     }     reverse(a.begin(), a.end());     reverse(b.begin(), b.end());     long long ans = 0;     long long settillnow = 0;     for (long long i = 0; i < n; i++) {       if (b[i] ==  1 ) {         settillnow++;       }       if (a[i] ==  1 ) {         long long c = pwr(2, n - 1 - i);         c = (c * settillnow) % mod;         ans += c;         ans %= mod;       }     }     cout << ans << endl;   }   