#pragma GCC optimize("Ofast")
#pragma GCC target("avx2")

char s[1024];
int count[2048];

int main(){
	int l=read(0,s,sizeof s)-1;
	for(long i=0;s[i];++i){
		for(long j=0;j<1024;++j){
			count[i+j]+=s[i]==s[j];
		}
	}
	int z=0;
	for(int i=0;i<=2000;++i){
		z=z>=count[i]?z:count[i];
	}
	printf("%d",z);
}