#include <stdio.h>

int main(){
    int n;
    int ans;
    int max;
    int c;
    scanf("%d",&n);
    for (int i=0;i<n;i++) {
        scanf("%d",&c);
        max=(c>max)?c:max;
        ans+=(c>>1);
    }
    ans+=(max>>1)+(max&0x1);
    printf("%d\n",ans);
}