选择最大值即可

#include <bits/stdc++.h>
using namespace std;
int main() {
    int n, x = 0, y = 0, a;
    scanf("%d", &n);
    for (int i = 1;i <= n; i++) scanf("%d", &a), x = max(x, a);
    scanf("%d", &n);
    for (int i = 1;i <= n; i++) scanf("%d", &a), y = max(y, a);
    printf("%d %d", x, y);
    return 0;
}