Score Validation

#include<stdio.h>
int main()
{
    float num=0,count=0,sum=0,avg;
    while(count!=2)
    {
        scanf("%f",&num);
        if(num>=0 && num<=10)
        {
            sum=sum+num;
            count++;
        }
        else
        {
            printf("nota invalida\n");
            num=0;
        }
    }
    avg=sum/2;
    printf("media = %.2f\n",avg);
    return 0;
}