using System;
using System.Collections.Generic;
using System.Linq;
using Debug = System.Diagnostics.Debug;
//using System.Numerics;
//using static System.Math;
using Number = System.Int64;

using C = System.Double;
using V = System.Double;

namespace Program {
    public class Solver {
        //const long MOD = (long)1e9 + 7;
        public void Solve() {
            var n = ri;
            var p = Enumerate(n, x => rl);
            var q = Enumerate(n, x => rl);
            var A = new long[n];
            A[0] = p[0];
            for (int i = 1; i < n; i++)
                A[i] = A[i - 1] + p[i];
            a = A.Take(n - 1).ToList();
            var res = f(0, n - 1); res.Add(A.Last());
            p[0] = res[0];
            var ok = true;
            for (int i = 1; i < n; i++) {
                p[i] = res[i] - res[i - 1];
                ok &= p[i] >= q[i];
            }
            if (ok) Console.WriteLine(inv);
            else Console.WriteLine(-1);
        }
        List<long> a;
        long inv;
        List<long> f(int l, int r) {
            if (r - l == 1) return new List<long>() { a[l] };
            var m = (l + r) / 2;
            var L = f(l, m);
            var R = f(m, r);
            var ret = new List<long>();
            var p = 0; var q = 0;
            while (p < L.Count && q < R.Count) {
                if (L[p] <= R[q]) {
                    ret.Add(L[p++]);
                }
                else {
                    inv += L.Count - p;
                    ret.Add(R[q++]);
                }
            }
            while (p < L.Count) ret.Add(L[p++]);
            while (q < R.Count) ret.Add(R[q++]);
            return ret;
        }
        const long INF = 1L << 60;
        //int[] dx = { 1, 0, -1, 0 };
        //int[] dy = { 0, 1, 0, -1 };
        //*
        int ri { get { return sc.Integer(); } }
        long rl { get { return sc.Long(); } }
        double rd { get { return sc.Double(); } }
        string rs { get { return sc.Scan(); } }
        //*/

        public IO.StreamScanner sc = new IO.StreamScanner(Console.OpenStandardInput());
        static T[] Enumerate<T>(int n, Func<int, T> f) { var a = new T[n]; for (int i = 0; i < n; ++i) a[i] = f(i); return a; }
        static public void Swap<T>(ref T a, ref T b) { var tmp = a; a = b; b = tmp; }
    }
}

#region main
static class Ex {
    static public string AsString(this IEnumerable<char> ie) { return new string(ie.ToArray()); }
    static public string AsJoinedString<T>(this IEnumerable<T> ie, string st = " ") {
        return string.Join(st, ie.Select(x => x.ToString()).ToArray());
        //return string.Join(st, ie);
    }
    static public void Main() {
        Console.SetOut(new System.IO.StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false });
        var solver = new Program.Solver();
        solver.Solve();
        Console.Out.Flush();
    }
}
#endregion
#region Ex
namespace Program.IO {
    using System.Globalization;
    using System.IO;
    using System.Text;
    public class Printer: StreamWriter {
        public override IFormatProvider FormatProvider { get { return CultureInfo.InvariantCulture; } }
        public Printer(Stream stream) : base(stream, new UTF8Encoding(false, true)) { }
    }
    public class StreamScanner {
        public StreamScanner(Stream stream) { str = stream; }
        public readonly Stream str;
        private readonly byte[] buf = new byte[1024];
        private int len, ptr;
        public bool isEof = false;
        public bool IsEndOfStream { get { return isEof; } }
        private byte read() {
            if (isEof) return 0;
            if (ptr >= len) { ptr = 0; if ((len = str.Read(buf, 0, 1024)) <= 0) { isEof = true; return 0; } }
            return buf[ptr++];
        }
        public char Char() { byte b = 0; do b = read(); while ((b < 33 || 126 < b) && !isEof); return (char)b; }

        public string Scan() {
            var sb = new StringBuilder();
            for (var b = Char(); b >= 33 && b <= 126; b = (char)read())
                sb.Append(b);
            return sb.ToString();
        }
        public string ScanLine() {
            var sb = new StringBuilder();
            for (var b = Char(); b != '\n' && b != 0; b = (char)read())
                if (b != '\r') sb.Append(b);
            return sb.ToString();
        }
        public long Long() { return isEof ? long.MinValue : long.Parse(Scan()); }
        public int Integer() { return isEof ? int.MinValue : int.Parse(Scan()); }
        public double Double() { return isEof ? double.NaN : double.Parse(Scan(), CultureInfo.InvariantCulture); }
    }
}
#endregion


Measured memory_bytes: 18896