#include <algorithm>#include <iomanip>#include <iostream>using namespace std;void solve(void) { int n; cin >> n; int sum = 0; while (n--) { int h, m; cin >> h >> m; sum += h * 60 + m; } int ans = 1e9; for (int i=0; i<=sum/180+2; i++) { int cnt = max(0, (sum-i*240+179)/180); ans = min(ans, i*1090+cnt*915); } for (int i=0; i<=sum/240+2; i++) { int cnt = max(0, (sum-i*180+239)/240); ans = min(ans, i*915+cnt*1090); } cout << ans/100 << '.' << setw(2) << setfill('0') << ans % 100;}int main(void) { ios::sync_with_stdio(false); cin.tie(nullptr); solve(); return 0;}