#include <bits/stdc++.h>

#define pb push_back
#define mp make_pair
#define sz(x) (int)(x).size()
#define li long long
#define ld long double
#define x first
#define y second
#define pt pair<int, int>
#define pll pair<ll, ll>
#define forn(i, t) for(int i = 0; i < (t); i++)
#define fore(i, f, t) for(int i = (f); i < (t); i++)
#define forr(i, f, t) for(int i = (f) - 1; i >= (t); i--)
#define all(x) (x).begin(), (x).end()
#define ins insert

using namespace std;


const int INF = 1e9 + 7;
const int MOD = 1e9 + 7;
const li INF64 = 1e18;
const ld EPS = 1e-7;

mt19937 myrand(time(NULL));

const int N = 2000 + 21;

int n;
int a[N][5];


bool read(){
    if(scanf("%d", &n) != 1)
        return 0;
    forn(i, n){
        forn(j, 4)
            scanf("%d", &a[i][j]);
        a[i][4] = (a[i][1] > a[i][2] ? 0 : a[i][1] + a[i][3] > a[i][2] ? (a[i][2] + a[i][3] - a[i][1] + 2) / 2 : INF);
    }
    return 1;
}


int dp[N][N];


void solve(){
    forn(i, n + 1) forn(j, N) dp[i][j] = INF;
    dp[0][0] = 0;
    forn(i, n)
        forn(j, N){
            if (j + a[i][0] < N)
                dp[i + 1][j + a[i][0]] = min(dp[i + 1][j + a[i][0]], dp[i][j] + a[i][4]);
            dp[i + 1][j] = min(dp[i + 1][j], dp[i][j]);
        }
    int sum = 0, ans = INF;
    forn(i, n)
        sum += a[i][0];
    forn(i, N)
        if (sum - i < i)
            ans = min(ans, dp[n][i]);
    if (ans == INF)
        printf("impossible\n");
    else
        printf("%d\n", ans);
}


int main(){
    #ifdef _DEBUG
        freopen("input.txt", "r", stdin);
    #endif
    while(read())
        solve();
    return 0;
}