#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<iostream>
#include<vector>
#include<cstdint>
#include<cstddef>
using namespace std;
using i32 = int_fast32_t;
using i64 = int_fast64_t;
using usize = size_t;
#define rep(i, n) for (usize i = 0; i < (usize)(n); i++)
#define all(a) (a).begin(),(a).end()
#define rall(a) (a).rbegin(),(a).rend()
using P = pair<i64,i64>;

int main(){
ios::sync_with_stdio(false);
std::cin.tie(nullptr);
usize n;
cin >> n;
vector<usize> a(n);
i64 right = 0;
i64 stone_exists = 0;
rep(i,n){
    cin >> a[i];
    if(a[i] == i + 1)right = i + 1;
    if(a[i] != 0)stone_exists = i + 1;
}
usize cnt = 0;
rep(i,n){
    if(a[i] >= i + 1 && i != 0){
        cnt++;
    }
}
if(cnt >= 2 || right != stone_exists){
    cout << "No" << endl;
}
else{
    cout << "Yes" << endl;
}
}