#include <stdio.h>

int main(void){
  int n,count = 0,count1 = 0;
  
  scanf("%d",&n);
  char s;
  int flag[n];
  int i;
  int u = 0;
  
  for(i = 0;i < n;i++){
   scanf(" %c",&s);
    if(s == '#'){
     flag[i] = 1;
      u++;
    }else{
     flag[i] = 0;
    }
  }
  
  for(i = 0;i < n;i++){
    if(flag[i] == 1){
      break;
    }
  }
  
  for(int m = i;m < n;m++){
    if(flag[m] == 0){
      count++;
    }
  }
  
  for(m = (n -1);m >= 0;m--){
    if(flag[m] == 0){
      break;
    }
    u--;
  }
  
  if(count < u){
  printf("%d\n",count);
  }else{
   printf("%d\n",u);
  }
  
  return 0;
}