求大佬看看，三目报错了

#include<bits/stdc++.h>
using namespace std;
long long a,b,c;
long long s; 
int main(){
	cin>>a>>b>>c;
	s=(long long)(3.5*(a+b+c)-a*2-b*3-c*4)/1.5+0.5;
	cout<<s<=0?0:s;
	return 0;
}