#include<stdlib.h>
#include<stdio.h>
#include<math.h>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
long long n;
int main()
{scanf("%I64d",&n);for(long long i=1;;i++)if(i*(i+1)/2>=n)return printf("%I64d\n",n-i*(i-1)/2),0;
}

#include<stdlib.h>
#include<stdio.h>
#include<math.h>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int h,m,a;
void print(int k)
{if(k<10)printf("0%d",k);else printf("%d",k);
}
int main()
{scanf("%d:%d%d",&h,&m,&a);m+=a;h+=m/60;m%=60;h%=24;print(h);printf(":");print(m);return 0;
}

#include<stdlib.h>
#include<stdio.h>
#include<math.h>
#define N 1000001
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int n,m,a[N],l,r,x,_,f[N];
int main()
{scanf("%d%d",&n,&m);for(int i=1;i<=n;i++){scanf("%d",&a[i]);f[i]=f[i-1]+(a[i]!=a[i-1]);}for(int i=1;i<=m;i++){scanf("%d%d%d",&l,&r,&x);if(f[l]==f[r] && a[l]==x){printf("-1\n");continue;}if(a[l]!=x)printf("%d\n",l);elseprintf("%d\n",upper_bound(f+l,f+r,f[l])-f);}return 0;
}

#include<stdlib.h>
#include<stdio.h>
#include<math.h>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
int n,a,b,f[1000001];
int main()
{scanf("%d",&n);a=1,b=n+1;for(int i=1;i<n;i++)f[a]=f[a+n-i]=i,a++,swap(a,b);f[a]=f[2*n]=n;for(int i=1;i<=2*n;i++)printf("%d%c",f[i],i==2*n?'\n':' ');return 0;
}

#include<bits/stdc++.h>
using namespace std;
#define N 500001
int n,u,v,ans,cnt,f[N];
vector<int>d[N];
void dfs(int cur,int pre,int dep)
{int x=0;for(auto nxt:d[cur])if(nxt!=pre)x=1,dfs(nxt,cur,dep+1);if(!x)f[++cnt]=dep;
}
int main()
{scanf("%d",&n);for(int i=2;i<=n;i++)scanf("%d%d",&u,&v),d[u].push_back(v),d[v].push_back(u);for(auto i:d[1]){cnt=0;dfs(i,1,0);sort(f+1,f+cnt+1);for(int i=2;i<=cnt;i++)f[i]=max(f[i],f[i-1]+1);ans=max(ans,f[cnt]+1);}return printf("%d\n",ans),0;
}

#include<stdlib.h>
#include<stdio.h>
#include<math.h>
#define N 1000005
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
#define LL long long
#define MOD 1000000007
LL n,k,t,ans,inv[N],y[N],f[N];
LL qow(LL X,LL Y){return Y?(Y&1?X*qow(X,Y-1)%MOD:qow(X*X%MOD,Y/2)):1;}
int main()
{scanf("%I64d%I64d",&n,&k);inv[1]=f[0]=t=1;for(LL i=2;i<=k+1;i++)inv[i]=(MOD-MOD/i)*inv[MOD%i]%MOD;for(LL i=1;i<=k+1;i++)f[i]=f[i-1]*inv[i]%MOD;for(LL i=1;i<=k+2;i++)y[i]=(y[i-1]+qow(i,k))%MOD;if(n<=k+2)return printf("%I64d\n",y[n]),0;for(LL i=1;i<=k+2;i++)t*=(n-i)%MOD,t%=MOD;for(LL i=1;i<=k+2;i++){LL s=((i-k)%2)?-1:1,res=y[i];res*=t*qow((n-i)%MOD,MOD-2)%MOD,res%=MOD;res*=f[i-1]*f[k+2-i]%MOD,res%=MOD;ans+=(res*s+MOD)%MOD,ans%=MOD;}printf("%I64d\n",ans);return 0;
}