#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int N = 1e5 + 10, mod = 1e9 + 7;
void solve() {
    ll n; cin >> n;
    for (ll i = 1; i; ++i) {
        if (i * (i + 1 ) / 2 >= n) {
            cout << i ;
            return ;
        }
    }
}
int main() {
    ios::sync_with_stdio(false), cin.tie(nullptr);
    solve();
    return 0;
}
#include<bits/stdc++.h>
using namespace std;

const int MaxN=1e9;
char Nss[20];
int main(){
	while(scanf("%s",Nss)!=EOF){
		int i, L=strlen(Nss)-1;
		while(L>=0 and Nss[L]=='0')
			L-=1;
		for(i=0; i<=(L>>1) and Nss[i]==Nss[L-i]; i+=1);
		puts( (L==-1 or i>(L>>1))? "Yes": "No");
	}
}