C++ :

#include <cstdio>
int main(){
    char s[128];
    if(scanf("%s",s)!=1) return 0;
    unsigned long long v=0;
    for(int i=0;s[i];i++) v = v*2 + (unsigned long long)(s[i]-'0');
    printf("%llu\n", v);
    return 0;
}