"IEEE 754 round-to-nearest-even"，需要手动对小数部分进行判断

#include <cmath>
#include <iomanip>
#include <iostream>

using namespace std;

int main()
{
    float f;
    cin >> f;

    float intpart, fractpart;
    fractpart = modff(f, &intpart);
    cout << fixed << setprecision(0) << ((fractpart >= 0.5f) ? (intpart + 1.0f) : intpart) << endl;
}