STL accumulate() With Example

#include<bits/stdc++.h>
using namespace std;
int mul(int x, int y)
{
    return x*y;
}
int main()
{
    int n;
    cout << "Enter Array Size :: ";
    cin >>n;

    int a[n];

    cout << "\nEnter Array Element :: ";
    for(int i=0;i<n;i++)
        cin >> a[i];

    int multiplication = accumulate(a, a+n, 1, mul);

    int substruction = accumulate(a, a+n, 0, minus<int>());

    cout << "\nMultiplication :: " << multiplication << "\n";

    cout << "\nSubstruction :: " << substruction << "\n";

    cout << "\nEnter String Array Size :: ";
    cin >> n;

    string s[n];

    cout << "\nEnter " << n << " String :: ";
    for(int i=0;i<n;i++)
        cin >> s[i];

    cout << "\nString is :: ";
    cout << accumulate(s, s+n, string("")) << "\n";

    return 0;
}