UVa 575 Skew Binary

#include <cstdio>
#include <cmath>
#include <iostream>
#include <cstring>

const int MAX = 50;
char num[50];

using namespace std;
int main ()
{
#ifndef ONLINE_JUDGE
freopen("in.txt", "r", stdin);
#endif

while(scanf("%s", num) == 1) {
int len = strlen(num);
int sum = 0;
for(int i=0; i<len; i++) {
sum += (num[i]-'0')*((1<<(len-i)) - 1);
}
if(sum == 0) break;
printf("%d\n",sum);
}
return 0;
}