#include <cstdio>

#define FOR( i, l, r) for(int i = (l)    ; i <  (r); i++)
#define FOR1(i, l, r) for(int i = (l)    ; i <= (r); i++)
#define REV( i, l, r) for(int i = (r) - 1; i >= (l); i--)
#define REV1(i, l, r) for(int i = (r)    ; i >= (l); i--)
#define INC( i, n) FOR( i, 0, n)
#define INC1(i, n) FOR1(i, 1, n)
#define DEC( i, n) REV( i, 0, n)
#define DEC1(i, n) REV1(i, 1, n)

typedef long long   signed int LL;
typedef long long unsigned int LU;

// ---- ----

char s[101];

int main() {
	scanf("%s", s);
	
	int len = 0;
	while(s[len] != '\0') { len++; }
	
	int ans = 0;
	INC(i, len) { if(s[i] == 'n') { ans++; } }
	
	printf("%d\n", ans);
	
	return 0;
}