import java.io.*;
import java.util.*;
public class Solution {
static Map map;
static {
String s = "1";
int max = 800;
map = new HashMap<>();
map.put("1", true);
for(int i=0;i=0;i--){
sum = carry + (s.charAt(i) - '0')*2;
carry = sum/10;
ans = (sum%10) + ans;
}
if(carry!=0) ans = carry + ans;
return ans;
}
}