import std;

void main () {
    auto A = readln.chomp.map!(a => a - '0').array;
    auto B = readln.chomp.map!(a => a - '0').array;
    A.reverse;
    int a = 0;
    foreach (i; 0 .. A.length) {
        a += (1 << i) * A[i];
    }
    B.reverse;
    int b = 0;
    foreach (i; 0 .. B.length) {
        b += (1 << i) * B[i];
    }

    int ans = 0;
    foreach (i; 0 .. 30) {
        ans |= ((1 << i) & a) ^ ((1 << i) & b);
    }

    writeln(ans);
}