#include <bits/stdc++.h> using namespace std; int main() { string a, b; cin >> a >> b; int a1 = a.size(), b1 = b.size(), ans = 0; for (int i = 0; i < a1; i++) { if (a[i] == b[i]) { continue; } else { ans++; a[i] = b[i]; if (a[i + 1] == '*') { a[i + 1] = 'o'; } else { a[i + 1] = '*'; } } } cout << ans << endl; return 0; }