#include <iostream>

using namespace std;

int main(){

int a, b, c;

while (cin >> a >> b >> c){

if (a!=0) a=1;

if (b!=0) b=1;

bool found=false;

if ((a&b)==c){

found=true;

cout <<"AND\n";

}

if ((a|b)==c){

found=true;

cout <<"OR\n";

}

if ((a^b)==c){

found=true;

cout <<"XOR\n";

}

if (!found)

cout <<"IMPOSSIBLE\n";

}

return 0;

}