'use strict';
process.stdin.on('data', function(chunk) {
    var inputs = chunk.toString().trim().split('\n');
    for (var i = 0; i < inputs.length; i++) {
    	if (inputs[i] === '0 0'){
    		break;
    	}
    	var cols = inputs[i].split(' ').map(Number);
        console.log(
        cols.sort(function(a,b){
        	return a - b;
        }).join(' ')
  );
    }
});
process.stdin.resume();
process.stdin.setEncoding('utf8');