#include <iostream>
using namespace std;
int main(){
    double x,y;
    int n,a;
    cin>>x>>y>>n;
    a=(n*x)/y;
    cout<<a<<endl;
    return 0;
}

#include<bits/stdc++.h>
#include<cstring>
#include<queue>
#include<set>
#include<stack>
#include<vector>
#include<map>
#define ll long long
using namespace std;
const int N=1e5+10;
const int M=2023;
const int inf=0x3f3f3f3f;
double x,y,n;
int main()
{
	cin>>x>>y>>n;
	cout<<floor(x*n/y);
	return 0;
}

要向下取整

#include <iostream>
#include <stdio.h>
#include <iomanip>
#include <math.h>
using namespace std;
const int N = 1e6 + 10;
const int INF = 0x3f3f3f3f;
int main()
{
	float x , y;
	int n;
	cin >> x >> y >> n;
	n = (x * n) / y;
	cout << n;
	return 0;
}

#include <bits/stdc++.h>

using namespace std;

int main()
{
    double x, y;
    long n;

    cin >> x >> y >> n;

    long long m = x * n / y;

    cout << m;

    return 0;
}

P824 做衣服

这里有一个误区，setprecision(0)并不是直接舍去小数部分，而是四舍五入至个位，所以可以直接在实数结果前强转成int

蒟蒻のAC代码

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

#include
using namespace std;
int main(){
    double x,y;
    int n,m;
	cin>>x>>y;
	cin>>n;
	m=x*n/y;
    cout<<m;
}