题解 | #汽水瓶#

#include <stdio.h>
int main(void)
{
    int b,c,n;
    while(scanf("%d",&n)!=EOF){
        b=n;
        if(b>=2){
            c=b/2;
            printf("%d\n",c);
        }
        else{
            printf("\n");
        }
    }
}