// tested by Hightail - https://github.com/dj3500/hightail
import std.stdio, std.string, std.conv, std.algorithm;
import std.range, std.array, std.math, std.typecons, std.container, core.bitop;

immutable mod = 10^^9 + 7;
immutable inf = 10^^9 + 7;

void main() {
    int n;
    int[] p;
    scan(n);
    p = readln.split.to!(int[]);
    p[] -= 1;

    auto s = new char[](n);

    foreach (i ; 0 .. n) {
        s[i] = (i == p[i] ? 'o' : 'x');
    }

    debug {
        writeln(s);
    }

    long ans = s.split('x').map!(w => (w.length.to!int + 1) / 2).sum(0L);

    writeln(ans);
}



void scan(T...)(ref T args) {
    string[] line = readln.split;
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}



void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
} 