京东

// sa.cpp.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"
#include<iostream>
#include <cstdio>
#include <iostream>
using namespace std;
inline bool IsOne(int &side, unsigned int &number)
{
    return ((1 << side) & number) > 0;
}

void Funs(unsigned int n)
{
    if (n <= 0)
    {
        printf("error\n");
        return ;
    }
    ++n;
    char chrResult[33];
    int iSide, iCount;
    iSide = 31;
    iCount = 0;
    while (iSide >= 0 && !IsOne(iSide, n)) --iSide;
    --iSide;
    while (iSide >= 0)
    {
        if(IsOne(iSide, n))
        {
            chrResult[iCount++] = '7';
        }
        else
        {
            chrResult[iCount++] = '4';
        }
        --iSide;
    }
    chrResult[iCount] = '\0';
    printf("%s\n", chrResult);
    return;
}

int main()
{
    unsigned int n;
    while (scanf("%u", &n) != EOF)
    {
        Funs(n);
    }

    return 0;
}