var num=window.prompt();  
var str = num.toString();  
var result = [str[0]];  
    
for(var x=1; x<str.length; x++)  
  {  
    if((str[x-1]%2 === 0)&&(str[x]%2 === 0))  
     {  
      result.push('-', str[x]);  
     }  
    else  
     {  
      result.push(str[x]);  
     }  
  }  
console.log(result.join(''));  