#include <stdio.h>
#include <algorithm>

using namespace std;

int M;
int C[76][76];
int used[76];

int dfs(int u, int t, int f) {
    if (u == t) return f;
    used[u] = 1;
    for (int i = 0; i < M; i++) {
        if (C[u][i] > 0 && !used[i]) {
            int d = dfs(i, t, min(f, C[u][i]));
            if (d > 0) {
                C[u][i] -= d;
                C[i][u] += d;
                return d;
            }
        }
    }
    return 0;
}

int flow(int s, int t) {
    int res = 0;
    for (;;) {
        for (int i = 0; i < M; i++) {
            used[i] = 0;
        }
        int f = dfs(s, t, 1e9);
        if (f == 0) return res;
        res += f;
    }
}

int N;
int A[37], B[37];

int main() {
    scanf("%d", &N);
    int a = 0, b = 0;
    for (int i = 1; i < N; i++) {
        scanf("%d %d", &A[i], &B[i]);
        a += B[i];
        b += A[i];
    }
    M = N * 2 + 2;
    int s = M - 2;
    int t = M - 1;
    int k = 0;
    for (int ii = 1 << 18; ii >= 1; ii >>= 1) {
        if (a - (k + ii) < 0 || b - (k + ii) < 0) continue;
        A[0] = a - (k + ii);
        B[0] = b - (k + ii);
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < N; j++) {
                if (i != j) {
                    C[i][j + N] = 1e9;
                    C[j + N][i] = 0;
                }
            }
        }
        for (int i = 0; i < N; i++) {
            C[s][i] = A[i];
            C[i + N][t] = B[i];
        }
        int total = 0;
        for (int i = 0; i < N; i++) {
            total += A[i];
        }
        if (total == flow(s, t)) {
            k += ii;
        }
    }
    printf("%d\n", k + 1);
    return 0;
}