#include <stdio.h>

int main(){
	char str[100];
	int i = 0;
	int num = 0;
	scanf("%s",str,100);

	while(str[i] != '\0'){
		if(str[i] == 'n'){
			num++;
		}
		i++;
	}
	printf("%d\n",num);
	return 0;
}