#include<bits/stdc++.h> using namespace std; int main(){ /** long long a,b,c; cin>>a>>b>>c; if(a%c==0 && b%c==0){ cout<<a*b/(c*c); }else{ cout<<-1; } double h=100; for(int i=1;i<=10;i++){ h = h/2; } printf("%.6lf",h); int a=1; int n; cin>>n; for(int i=0;i<n-1;i++){ a=a+i; } cout<<a<<endl; int a=10000; int n; cin>>n; if(n%2==0){ a=a-(n/2-1)*2; } else{ a=a-(n/2)*1; } cout<<a; int n; int s=1; cin>>n; for(int i=2;i*i<=n;i++){ if(n%i==0){ s = 0; break; } } if(s==1) cout<<"Yes"; else cout<<"o"; **/ int s=0; int n=1; while(s<=1000){ s+=n; n++; } cout<<n-1<<endl; return 0; }