#include<cstdio>
#include<string>

#define MAXN 200010

int main(void)
{
    short int a[MAXN];
    int n = 0;
    int key;
    while(scanf("%2x", &a[n++]) == 0);
    n = (n-1) / 2;
    key = 0x20 ^ a[n];
    printf("%x", key);
    for(int i = 0; i < n; ++i){
        key ^= a[i];
        key ^= a[n+i+1];
	printf("%X", key);
    }
    return 0;
}