a = document.getElementsByClassName('_53n').length;
b = 0;
c = [];
for(i=0;i<a;i++) {
 if(parseInt(document.getElementsByClassName('_53n')[i].innerHTML) > b) b = parseInt(document.getElementsByClassName('_53n')[i].innerHTML);
 c[i] = parseInt(document.getElementsByClassName('_53n')[i].innerHTML);
}
console.log(b);