def main():
    passengers = []
    for _ in range(int(input())-1):
        dep, arr = map(int, input().split())
        passengers.append((dep, arr))

    dep_sum = sum(dep for dep, _ in passengers)
    arr_sum = sum(arr for _, arr in passengers)
    print(min(dep_sum, arr_sum) + 1)


if __name__ == "__main__":
    main()