def primo(p):
c = p
for x in range(2, p):
if p%x == 0:
c = 0
return c
def mayor(n):
c = 3
while c < n//2:
r = primo(c)
c += 1
return r
print(mayor(100))
ZGVmIHByaW1vKHApOgoJYyA9IHAKCWZvciB4IGluIHJhbmdlKDIsIHApOgoJCWlmIHAleCA9PSAwOgoJCQljID0gMAoJcmV0dXJuIGMKICAgCmRlZiBtYXlvcihuKToKCWMgPSAzCgl3aGlsZSBjIDwgbi8vMjoKCQlyID0gcHJpbW8oYykKCQljICs9IDEKCXJldHVybiByCnByaW50KG1heW9yKDEwMCkp