HDU 1219 AC me

#include<stdio.h>
int main()
{       char s[100001];
long a[26]={0},i;
while (gets(s)!=NULL)
{
i=0;
while (s[i])
{
if (s[i]>='a'&&s[i]<='z')
{
a[s[i]-'a']++;
}
i++;
}
for (i=0;i<26;i++)
{
printf("%c:%d\n",i+'a',a[i]);
a[i]=0;
}
printf("\n");
}
return 0;
}