Problem:
Score : 300 points

Problem Statement

There are N stones arranged in a row. Every stone is painted white or black.
A string S represents the color of the stones. The i-th stone from the left is white if the i-th character of S is ., and the stone is black if the character is #.

Takahashi wants to change the colors of some stones to black or white so that there will be no white stone immediately to the right of a black stone.
Find the minimum number of stones that needs to be recolored.

Constraints

1 \leq N \leq 2\times 10^5

S is a string of length N consisting of . and #.

Input

Input is given from Standard Input in the following format:

N
S

Output

Print the minimum number of stones that needs to be recolored.

Sample Input 1

3
#.#

Sample Output 1

1

It is enough to change the color of the first stone to white.

Sample Input 2

5
#.##.

Sample Output 2

2

Sample Input 3

9
.........

Sample Output 3

0

Solution in Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

class Main {
  public static void main(String[] args) {
    java.util.Scanner sc = new java.util.Scanner(System.in);
    int N = sc.nextInt();
    String S = sc.next();
int count=0;
String [] SArray = S.split("");

for(int i=0;i<N-1;i++){
if(SArray[i].equals("#")){
if(SArray[i].equals(SArray[i+1])){
}else{
count++;
}
}
}
println(count);
}

  

  /* 以下、標準出力用関数 */
  static public void print(byte what) { System.out.print(what); System.out.flush(); }
  static public void print(boolean what) { System.out.print(what); System.out.flush(); }
  static public void print(char what) { System.out.print(what); System.out.flush(); }
  static public void print(int what) { System.out.print(what); System.out.flush(); }
  static public void print(long what) { System.out.print(what); System.out.flush(); }
  static public void print(float what) { System.out.print(what); System.out.flush(); }
  static public void print(double what) { System.out.print(what); System.out.flush(); }
  static public void print(String what) { System.out.print(what); System.out.flush(); }
  static public void print(Object... variables) { StringBuilder sb = new StringBuilder(); for (Object o : variables) { if (sb.length() != 0) { sb.append(" "); } if (o == null) { sb.append("null"); } else { sb.append(o.toString()); } } System.out.print(sb.toString()); }
  static public void println() { System.out.println(); }
  static public void println(byte what) { System.out.println(what); System.out.flush(); }
  static public void println(boolean what) { System.out.println(what); System.out.flush(); }
  static public void println(char what) { System.out.println(what); System.out.flush(); }
  static public void println(int what) { System.out.println(what); System.out.flush(); }
  static public void println(long what) { System.out.println(what); System.out.flush(); }
  static public void println(float what) { System.out.println(what); System.out.flush(); }
  static public void println(double what) { System.out.println(what); System.out.flush(); }
  static public void println(String what) { System.out.println(what); System.out.flush(); }
  static public void println(Object... variables) { print(variables); println(); }
  static public void println(Object what) { if (what == null) { System.out.println("null"); } else if (what.getClass().isArray()) { printArray(what); } else { System.out.println(what.toString()); System.out.flush(); } }
  static public void printArray(Object what) { if (what == null) { System.out.println("null"); } else { String name = what.getClass().getName(); if (name.charAt(0) == '[') { switch (name.charAt(1)) { case '[': System.out.println(what); break; case 'L': Object poo[] = (Object[]) what; for (int i = 0; i < poo.length; i++) { if (poo[i] instanceof String) { System.out.println("[" + i + "] \"" + poo[i] + "\""); } else { System.out.println("[" + i + "] " + poo[i]); } } break; case 'Z': boolean zz[] = (boolean[]) what; for (int i = 0; i < zz.length; i++) { System.out.println("[" + i + "] " + zz[i]); } break; case 'B': byte bb[] = (byte[]) what; for (int i = 0; i < bb.length; i++) { System.out.println("[" + i + "] " + bb[i]); } break; case 'C': char cc[] = (char[]) what; for (int i = 0; i < cc.length; i++) { System.out.println("[" + i + "] '" + cc[i] + "'"); } break; case 'I': int ii[] = (int[]) what; for (int i = 0; i < ii.length; i++) { System.out.println("[" + i + "] " + ii[i]); } break; case 'J': long jj[] = (long[]) what; for (int i = 0; i < jj.length; i++) { System.out.println("[" + i + "] " + jj[i]); } break; case 'F': float ff[] = (float[]) what; for (int i = 0; i < ff.length; i++) { System.out.println("[" + i + "] " + ff[i]); } break; case 'D': double dd[] = (double[]) what; for (int i = 0; i < dd.length; i++) { System.out.println("[" + i + "] " + dd[i]); } break; default: System.out.println(what); } } else { System.out.println(what); } } System.out.flush(); }}