#include <algorithm>
#include <cstdint>
#include <iomanip>
#include <iostream>
#include <limits>
#include <numeric>
#include <sstream>
#include <string>
#include <unordered_map>
#include <utility>
#include <vector>
using i32 = std::int32_t;
using i64 = std::int64_t;
using u32 = std::uint32_t;
using u64 = std::uint64_t;
using pii = std::pair<i32, i32>;
using pll = std::pair<i64, i64>;
using vi = std::vector<i32>;
using vll = std::vector<i64>;
using vpii = std::vector<pii>;
using vpll = std::vector<pll>;
void solve();
int main()
{
std::cin.tie(nullptr)->sync_with_stdio(false);
solve();
}
double to_c(double f)
{
return static_cast<double>(5) * (f - 32) / 9;
}
void solve()
{
double f;
while (std::cin >> f)
{
std::cout << std::fixed << std::setprecision(3) << to_c(f) << std::endl;
}
}