#include <stdio.h>
int rd()
{
int rs = 0,c = getchar();
while (c < '0'||c > '9') c = getchar();
while (c >='0'&&c <= '9')
{
rs = (rs<<3)+(rs<<1)+c-'0';
c = getchar();
}return rs;
}
void wt(int t)
{
// 别忘了你叫什么
if (t > 9) wt(t/10);
putchar(t%10|48);
}
void solve()
{
int x = rd(),y = rd(),rs = x^y;
wt((rs&(-rs)));putchar('\n');
}
int main() {
int t = rd();
while (t--)solve(); return 0;
}

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