A question about C++

Question

I have just made a simple code about adding all the numbers that user entered;
how do i make it to subtract the first number with the other numbers that user have entered;

Below is my code;
#include <iostream>
using namespace std;

int main(){

int a;
int x;
int y;
int total;

cout << "What do you want to do with these numbers" << endl; // sum = 1, sub = 2, multi = 3, div =4
cin >> a;
cout << "How many number do you have to perform?" << endl;
cin >> x;

if ( a == 1) {
for (int z = 1; z <= x; z++) {
cin >> y;
total += y;
}

}

if ( a == 2) {
for (int z = 1; z <= x; z++) {
cin >> y;
total -= y;
}

}

cout << total;

return 0;
}

Answer 1

You can: cin >> y; total=y;
just before the loop starts and make the condition z<x

Answer 2

As Stefano said, you have to set total=y before to enter the loop.
And the same thing for division.

For the addition you need to set total to zero otherwise the sum starts from a garbage value.
And for multiplication you need to set the total to 1 so that in the loop you can do total*=y;