Caesar cipher

#include <iostream>
using namespace std;
int main()
{intk,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;
return0;
}