#include <stdio.h>

int main() {
    int n1, n2;
    scanf("%d %d", &n1, &n2);

    int arr1[n1], arr2[n2];

    for (int i = 0; i < n1; i++) {
        scanf("%d", &arr1[i]);
    }

    for (int i = 0; i < n2; i++) {
        scanf("%d", &arr2[i]);
    }

    int merged[n1 + n2];
    int i = 0, j = 0, k = 0;

    while (i < n1 && j < n2) {
        if (arr1[i] < arr2[j]) {
            merged[k++] = arr1[i++];
        } else {
            merged[k++] = arr2[j++];
        }
    }

    while (i < n1) {
        merged[k++] = arr1[i++];
    }

    while (j < n2) {
        merged[k++] = arr2[j++];
    }

    int mid = (n1 + n2) / 2;
    double median = (double)merged[mid];

    if ((n1 + n2) % 2 == 0) {
        median = (merged[mid - 1] + merged[mid]) / 2.0;
    }

    printf("%.1f\n", median);

    return 0;
}