#include <iostream>
#include <cmath>
using namespace std;
 
void create(int *&x,int n){
	x=new int[n];
}
void enter(int *x,int n){
	for(int i=0;i<n;++i){
		cin>>x[i];
	}
}
void print(int *x,int n){
	for(int i=0;i<n;++i){
		cout<<x[i]<<" ";
	}
}
void add(int *x,int *y,int *z,int n){
	for(int i=0;i<n;++i){
		z[i]=x[i]+y[i];
	}
}
void subtract(int *x,int *y,int *z,int n){
	for(int i=0;i<n;++i){
		z[i]=x[i]-y[i];
	}
}
double length(int *x,int n){
	double sum=0;
	for(int i=0;i<n;++i){
	sum+=x[i]*x[i];
}
return(sqrt(sum));
}
double dot(int *x,int *y,int n){
	int sum=0;
	for(int i=0;i<n;++i){
		sum+=(x[i]*y[i]);
	}
	return(sum);
}
int main() {
int *x,*y,*z,n;
cin>>n;
/*create(x,n);
create(y,n);
create(z,n);
enter(x,n);
enter(y,n);
subtract(x,y,z,n);
print(z,n);*/
create(x,n);
enter(x,n);
create(y,n);
enter(y,n);
cout<<dot(x,y,n);
 
	return 0;
}

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