#include<stdio.h>

int main(void){
  int i;
  char S[101];
  int flag = 0, n = 0;
  scanf("%s", S);
  for(i = 0; S[i] != '\0'; i++){
    if(S[i] == 'c') flag = 1;
    if(flag == 1 && S[i] == 'w') flag = 2;
    else if(flag == 2 && S[i] == 'w'){
      flag = 3;
      break;
    }
    if(flag != 0) n++;
  }
  if(n == 0) printf("-1\n");
  else printf("%d\n", n);
  return 0;
}