#include <stdio.h>

int main(void) {
	char str[101];
	int i, count;
	int flag_c = 0, flag_w1 = 0, flag_w2 = 0;
	
	scanf("%s", str);
	i = 0;
	count = 0;
	while(str[i] != '\0'){
		if(str[i] == 'c'){
			count++;
			flag_c = 1;
		}
		else if(flag_c == 1 && flag_w1 == 0 && str[i] == 'w'){
			flag_w1 = 1;
			count++;
		}
		else if(flag_c == 1 && flag_w1 == 1 && flag_w2 == 0 && str[i] == 'w'){
			count++;
			flag_w2 = 1;
			flag_c = 0;
			flag_w1 = 0;
		}
		else if(flag_c == 1 || flag_w1 == 1){
			count++;
		}
		i++;
	}
	if(flag_w2 == 1){
		printf("%d\n", count);
	}
	else{
		printf("-1\n");
	}

    return 0;
}