#include

int main()
{
    int a[100],i,n;
    double c,b;
    while(scanf("%d",&n) !=EOF)
    {

b = 0; 

每一次的b都要從新計算!! 

**************************    
*    for (i=0;i<n; i++)             *  
*    {                                      *      
*       scanf("%d",&a[i]);          *      
*    }                                      *

*    for(i=0;i<n; i++)              *

*    {                                      *
*      b += a[i];                       *

*    }                                      *
**************************

上面的可以合在一起 

    c = b/n;
    if (c<=59)
    {
             printf("yes\n");
             }
             else if(c>59)
             {
                 printf("no\n");
                 }
    }

return 0 ;

}