#include <math.h>
#include <iostream>
#include <string>
#include <vector>
#include <cstring>
#include <algorithm>
using namespace std;

string s1;
vector<int> v1;
char a[2];
char b[2];

bool jud_A(char x)
{
	if (x >= 'A' && x <= 'Z')
		return true;
	else return false;
}

bool jud_num(char x)
{
	if (x >= '0' && x <= '9')
		return true;
	else return false;
}

double tr_to_k(vector<int>& v)//1, 2, 3
{					  //0, 1, 2
	double res = 0;
	for (int i = v.size() - 1, j = 0; i >= 0; i--)
	{
		res += pow(10, j) * v[i];
		j++;
	}//得到res
	if (!strcmp(a, "GB"))
	{
		return res * 1024 * 1024 * 1024;
	}
	else if (!strcmp(a, "MB"))
	{
		return res * 1024 * 1024;
	}
	else if (!strcmp(a,"KB"))
	{
		return res * 1024;
	}
	else//k不需要转换
		return res;
}

int main()
{
	cin >> s1;
	int tmp;
	for (int i = 0; i < s1.size(); i++)
	{
		if (jud_num(s1[i])) {
			v1.push_back(s1[i] - '0');
			tmp = i;
		}
		else break;
	}//收入第一个数
	for (int i = tmp+1, j = 0; i < s1.size(); i++)
	{
		if (jud_A(s1[i])) {
			a[j] = s1[i];
			j++;
			tmp = i;
		}
		else break;
	}//收入单位
	for (int i = s1.size()-1, j = 1; i >= 0; i--)
	{
		if (jud_A(s1[i])) {
			b[j] = s1[i];
			j--;
			tmp = i;
		}
		else break;
	}//收入单位
	

	double tmp_ans = tr_to_k(v1);

	if (!strcmp(b, "GB"))
	{
		printf("%.6lf", (tmp_ans / 1024 / 1024 / 1024));
		return 0;
	}
	else if (!strcmp(b, "MB"))
	{
		printf("%.6lf", tmp_ans / 1024 / 1024);
		return 0;
	}
	else if (!strcmp(b, "KB"))
	{
		printf("%.6lf", tmp_ans / 1024);
		return 0;
	}
	else//k不需要转换
		printf("%.6lf", tmp_ans);
	return 0;
}

只能过样例的蒟蒻来求助大佬们看一下