#include <iostream> #include <string> #include <algorithm> using namespace std; int main() { string skew; while (cin >> skew) { reverse(skew.begin(), skew.end()); int res = 0; for (int i = 0; i < skew.size(); ++i) res += (skew[i]-'0') * ((2 << i) - 1); //并不需要去用pow,2的...