#include <bits/stdc++.h>
using namespace std;
#define sp << " " <<
#define int long long
#define vi vector<int>
#define F(xxx,yyy) for (int xxx=1;xxx<=yyy;xxx++)
#define pii pair<int,int>
const int N = 1e5+1,inf = 1e18;
void solve() {
string nn;
cin >> nn;
if (nn.size() <= 19) {
int n = stoi(nn);
if(n<=1e18) {
int l=1;
int r=2e9;
while (l<=r) {
int m = (l+r)/2;
if (m*(m+1)/2 <= n) l = m+1;
else r = m-1;
}
int x = r*(r-1)/2;
cout << n+x+(n-r*(r+1)/2)/2 << endl;
}
else cout << -1 << endl;
}
else cout << -1 << endl;
}
signed main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#ifdef Local
freopen("in","r",stdin);
freopen("out","w",stdout);
#endif
int t = 1;
//cin >> t;
F(i,t) solve();
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
0 ms |
344 KB |
Output is correct |
| 2 |
Correct |
0 ms |
344 KB |
Output is correct |
| 3 |
Incorrect |
0 ms |
348 KB |
Output isn't correct |
| 4 |
Halted |
0 ms |
0 KB |
- |
