#include <stdio.h>
int *A, stkTop;
int stkFunc (int opcode, int val)
{
    static int size=0, stkTop=0;
    switch (opcode)
    {
    case -1:
        size = val;
        break;
    case 0:
        if (stkTop < size ) A[stkTop++]=val;
        break;
    default:
        if (stkTop) return A[--stkTop];
    }
    return -1;
}
int main()
{
    int B[20];
    A=B;
    stkTop = -1;
    stkFunc (-1, 10);
    stkFunc (0, 5);
    stkFunc (0, 10);
    printf ("%dn", stkFunc(1, 0)+ stkFunc(1, 0));
}