I want stresstesting of this Python code. Can someone help me?

import sys

def min_refills(d, m, n, st, f):
     if d >= m:
          return 0
     if m == 0:
          return -1
     s = round(d/m, 3)
     si = int(d/m)
     sm = round(s - si, 3)
     n = len(st)
     y, i, r = 0, 0, 0
     j = -1
     o = 1
     f = "true"
     while(f == "true"):
          i = i +1
          j = j + 1
          x = int(st[i])- int(st[j])
          if (x == 1 and s == d and m ==1):
               r = d-1
               return r
          if ((sm == 0.000) and(x<= m) and (d-int(st[n-1]) <= m)):
               r = int(s-1)
               return r
          if((x<= m) and (d-int(st[n-1]) <= m)):
               r = int(s)
               if i > (n-2):
                    f = "false"
                    return r
          elif((x > m)or (d-int(st[n-1]) >m) or (s < n )):
               f = "false"
               r = -1
               return r


if __name__ == '__main__':
    d = int(input())
    m = int(input())
    n = int(input())
    f = "true"
    st =  sys.stdin.read().split()
    print(min_refills(d, m, n, st, f))