216.cpp

#include <stdio.h>
#include <queue>

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

    std::priority_queue<int> q;

    int v;
    while (n--)
        scanf("%d", &v), q.push(v);

    int a, b, count_unique = 0;
    while ((a = q.top(), q.pop(), a) && (b = q.top(), q.pop(), b))
        q.push(a-1), q.push(b-1), ++count_unique;

    printf("%d", count_unique);

    return 0;
}