import std;

void main() {
    int N, M;
    readf("%d %d\n", N, M);

    auto A = readln.chomp.split.to!(long[]);
    auto B = readln.chomp.split.to!(long[]);

    long res;
    int i, j;
    while (j < M) {
        if (A[i] > B[j]) {
            if (i == N - 1 && j == M - 1) {
                break;
            }

            res += A[i] - B[j];

            while (j < M - 1 && A[i] > B[j]) {
                ++j;
            }
        }
        else {
            while (i < N - 1 && A[i+1] < B[j]) {
                ++i;
            }

            long op = abs(B[j] - A[i]);
            if (i < N - 1 && op > A[i+1] - B[j]) {
                res += A[i+1] - B[j];
                ++i;
            }
            else {
                res += op;
                A[i] = B[j];
            }

            ++j;
        }
    }

    res.writeln;
}