#include <math.h>
double AttackerSuccessProbability (double q, int z)
{
double p = 1.0 - q;
double lambda = z * (q / p);
double sum = 1.0;
int i,k;
for (k = 0; k <= z; k++) {
    double poisson = exp(-lambda);
    for (i = 0; i <= k; i++) {
        poisson = lambda / i;