#include<bits/stdc++.h>
#define yy return 0;
using namespace std;
signed main(){
    long n;
    cin>>n;
    cout<<n;
    yy
}

#include<bits/stdc++.h> #define yy return 0; using namespace std; signed main(){ long n; cin>>n; cout<<n; yy }

惨痛教训！ 1.不开long long见祖宗 2.不能写float要写double

#include <iostream>
#include <cmath>
using namespace std;
int main(){
    double f;
    cin >> f;
    cout << (long long)f;
    return 0;
}

#include<iostream>
using namespace std;
int main(){
    double a,c;
    long long b;
    cin>>a;
    b=a;
    cout<<b;
}

#include<bits/stdc++.h>
using namespace std;
int main(){
    double x;
    cin>>x;
    cout<<(long long)(x);
}

import numpy as np a=np.float64(input()) a=int(a) print(a)

x = float(input())

rounded_x = int(x)

print(rounded_x)

因为输出小数点后 $9$ 位，所以printf("%.9lf",a/b);。

#include <bits/stdc++.h>
using namespace std;
int main()
{
    double a,b,c;
    cin>>a>>b;
    printf("%.9lf",a/b);
    return 0;
}