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

char*mmap();

int a[256];

main(){
	char*rp=mmap(0l,1000001,1,2,0,0ll);
	int c;
	while(c=*rp++){
		++a[c];
	}
	int z=a['t']<a['r']?a['t']:a['r'];
	z=z<a['e']>>1?z:a['e']>>1;
	printf("%d",z);
}