if(typeof(s)!=='string'){
        throw 's is not a number';
    }
    var num = {
        '1':1,
        '2':2,
        '3':3,
        '4':4,
        '5':5,
        '6':6,
        '7':7,
        '8':8,
        '9':9,
        '0':0
    }
    var result = Array.from(s).map(function(n){
           return num[n];
    }).reduce(function(x,y){
       return x * 10+ y;
    });
    return result;