// package atcoder.arc.arc062;

import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;


public class Main {
	public static void main(String[] args) {
		InputReader in = new InputReader(System.in);
		PrintWriter out = new PrintWriter(System.out);

		char[] d = in.nextToken().toCharArray();
		int D = 0;
		for (char c : d) {
			if (c == 'g') ;
			else {
				D++;
			}
		}
		out.println(d.length / 2 - D);
		out.flush();
	}

	static class InputReader {
		private InputStream stream;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;

		public InputReader(InputStream stream) {
			this.stream = stream;
		}

		private int[] nextInts(int n) {
			int[] ret = new int[n];
			for (int i = 0; i < n; i++) {
				ret[i] = nextInt();
			}
			return ret;
		}

		private int[][] nextIntTable(int n, int m) {
			int[][] ret = new int[n][m];
			for (int i = 0; i < n; i++) {
				for (int j = 0; j < m; j++) {
					ret[i][j] = nextInt();
				}
			}
			return ret;
		}

		private long[] nextLongs(int n) {
			long[] ret = new long[n];
			for (int i = 0; i < n; i++) {
				ret[i] = nextLong();
			}
			return ret;
		}

		private long[][] nextLongTable(int n, int m) {
			long[][] ret = new long[n][m];
			for (int i = 0; i < n; i++) {
				for (int j = 0; j < m; j++) {
					ret[i][j] = nextLong();
				}
			}
			return ret;
		}

		private double[] nextDoubles(int n) {
			double[] ret = new double[n];
			for (int i = 0; i < n; i++) {
				ret[i] = nextDouble();
			}
			return ret;
		}

		private int next() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		public char nextChar() {
			int c = next();
			while (isSpaceChar(c))
				c = next();
			if ('a' <= c && c <= 'z') {
				return (char) c;
			}
			if ('A' <= c && c <= 'Z') {
				return (char) c;
			}
			throw new InputMismatchException();
		}

		public String nextToken() {
			int c = next();
			while (isSpaceChar(c))
				c = next();
			StringBuilder res = new StringBuilder();
			do {
				res.append((char) c);
				c = next();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public int nextInt() {
			int c = next();
			while (isSpaceChar(c))
				c = next();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = next();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = next();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public long nextLong() {
			int c = next();
			while (isSpaceChar(c))
				c = next();
			long sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = next();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = next();
			} while (!isSpaceChar(c));
			return res * sgn;
		}

		public double nextDouble() {
			return Double.valueOf(nextToken());
		}

		public boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		public interface SpaceCharFilter {
			public boolean isSpaceChar(int ch);
		}
	}

	static void debug(Object... o) {
		System.err.println(Arrays.deepToString(o));
	}
}


Measured memory_bytes: 22996