程序代码：

#include <stdio.h>

int main( void )
{
    char bin[101];
    scanf( "%s", bin );

    unsigned long long dec[2] = { 0, 0 }; // base 10^18
    for( const char* p=bin; *p; ++p )
    {
        dec[1] = dec[0]*2/1000000000000000000 + dec[1]*2;
        dec[0] = dec[0]*2%1000000000000000000 + (*p-'0');
    }

    if( dec[1] != 0 )
        printf( "%llu%018llu\n", dec[1], dec[0] );
    else
        printf( "%llu\n", dec[0] );
}