public class Solution {
    public string Convert(string s, int numRows) 
    {
        if(string.IsNullOrWhiteSpace(s) || numRows == 1){
    		return s;
    	}
    	
        var s1 = "";
        int distance = 2 * numRows - 2;
    	
        for(var i = 0; i < numRows ; i++)
        {  
            for(int j = i; j < s.Length; j += distance)
            {  
                s1 += s[j];
                if(i !=0 && i != numRows - 1 && j + distance - 2 * i < s.Length){
    				s1 += s[j + distance - 2 * i];
    			}
            }                  
        }
        return s1;      
    }
}