function findMax(str) {
	if(str.length == 1) {
		return str;
	}
	let charObj = {};
	for(let i = 0; i < str.length; i ++) {
		if(!charObj[str.charAt(i)]) {
			charObj[str.charAt(i)] = 1;
		} else {
			charObj[str.charAt(i)] += 1;
		}
	}
	let maxChar = '';
	maxValue = 1;
	for(var k in charObj) {
		if(charObj[k] >= maxValue) {
			maxChar = k;
			maxValue = charObj[k];
		}
	}
	return maxChar;
}