Caesar cipher

#include <iostream>

using namespace std;

int main()

{int k,i;

char s[5];

 cin>>k;

 for(;k>=26;)k%=26;

 for(i=0;i<5;i++)

 { cin>>s[i];

     if(('a'<=s[i]&&s[i]<='z')||('A'<=s[i]&&s[i]<='Z'))

   {s[i]+=k;

      if(('z'<=s[i]&&s[i]<='z'+k)||('Z'<=s[i]&&s[i]<='Z'+k))

          s[i]-=26;

    }

 cout<<s[i];

 } 

 cout<<endl;

return 0;

}