import std.stdio;
import std.string;
import std.conv;
import std.typecons;
import std.algorithm;
import std.functional;
import std.bigint;
import std.numeric;
import std.array;
import std.math;
import std.range;
import std.container;
import std.ascii;
void times(alias pred)(int n) {
    foreach(i; 0..n) pred();
}
auto rep(alias pred, T = typeof(pred()))(int n) {
    T[] res = new T[n];
    foreach(ref e; res) e = pred();
    return res;
}

void main() {
    bool[] top = readln.chomp.map!(a => a=='p').array;
    int N = top.length.to!int;
    int[] ary = new int[N+1];
    foreach(i, e; top) {
        ary[i+1] = ary[i] + (e ? -1:1);
    }
    writeln(ary.back/2);
}
