#pragma GCC optimize(2)
#pragma GCC optimize(3)
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

int main()
{
    int n, m; scanf("%d%d", &n, &m);
    
    printf("%.2f", double (n - double(m * 0.8) ));
    
    return 0;
}

#pragma GCC optimize(2)
#pragma GCC optimize(3)
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

int main()
{
int n, m; scanf("%d%d", &n, &m);

printf("%.2f", double (n - double(m * 0.8) ));

return 0;
}