dev c++上命令报错

#include <iostream>
using namespace std;
int main ()
{
   int num1,num2,num3;
   char symbol;
   int num4;
   unsigned long long num5 = 1;
   system("color 5");
   cout<<"输入数字"<<endl;
   cin>>num1;
   cin>>num2;
   cout<<"选择符号"<<endl;
   cin>>symbol;
   switch(symbol)
   {
      case '+':
         num3=num1+num2;
         cout<<num3;
         break;
      case '-':
         num3=num1-num2;
         cout<<num3;
         break;
      case '*':
         num3=num1*num2;
         cout<<num3;
         break;
      case '/':
         if (num2==0)
         {
            cout<<"this is zero"<<endl;
         }
         else
         {
            num3=num1/num2;
            cout<<num3;
         }
         break;
      case 'a':
         cout<<"输入数字"<<endl;
         cin>>num4;
         for (int i = 1; i <= num4; ++i)
         {
            num5 *= i;
         }
         cout<<num5;
      case '%':
         cout<<num1%num2<<endl;
      default:
         cout<<"no"<<endl;
   }
   return 0;
}

case 'a'后面没加break