Stack implementation code...how do i put it on user input?

#include 
using namespace std;

int st[100],top=-1;

void push(int x)
{
    st[++top] = x ;
}

void pop()
{
    if(top==-1) printf("Stack Overflow");
    else  printf("Delete = %d\n",st[top--]);
}

int main()
{
    push(10);
    push(100);
    push(-25);
    pop();
    pop();
    return 0;
}

int main()
{
int n;
cin >> n;
    push(10);
    push(100);
    push(-25);
    pop();
    pop();
    return 0;
}