#include <bits/stdc++.h>
using namespace std;

int main(){
int pizzaSize[] = {8, 10 , 12};
int pizzaPrice[] = {10, 13, 16};

int sum = 0;
for (int i = 0; i < sizeof(pizzaSize) / sizeof(pizzaSize[0]); i++) {
sum += pizzaSize[i];
}
int meanX = sum/3;

int sum1 = 0;
for (int i = 0; i < sizeof(pizzaPrice) / sizeof(pizzaPrice[0]); i++) {
sum1 += pizzaPrice[i];
}
int meanY = sum1/3;

int deviatonX = pizzaSize[0] - meanX;
int deviatonX1 = pizzaSize[1] - meanX;
int deviatonX2 = pizzaSize[2] - meanX;

int deviatonY = pizzaPrice[0] - meanY;
int deviatonY1 = pizzaPrice[1] - meanY;
int deviatonY2 = pizzaPrice[2] - meanY;

int productOfDeviations = deviatonX * deviatonY;
int productOfDeviations1 = deviatonX1 * deviatonY1;
int productOfDeviations2 = deviatonX2 * deviatonY2;

double sumOfProductOfDeviations = productOfDeviations + productOfDeviations1 + productOfDeviations2;

double squareOfDeviations = deviatonX * deviatonX;
double squareOfDeviations1 = deviatonX1 * deviatonX1;
double squareOfDeviations2 = deviatonX2 * deviatonX2;

double squareOfDeviationsforX = squareOfDeviations + squareOfDeviations1 + squareOfDeviations2;

double m = sumOfProductOfDeviations / squareOfDeviationsforX;

double b = meanY - (m * meanX);

double X;
cout << "pizza size: " ;
cin >> X;

double y = m * X + b;

cout << "predicted price: " ;
cout << y << endl;
}