layout(matrix(1:2, ncol = 2))

plot(survfit(Surv(time, event) ~ group, data = g3),
main = "Grade III Glioma", lty = c(2, 1),
ylab = "Probability",
xlab = "Survival Time in Month", legend.bty = "n", legend.text = c("Control", "Treated"))

plot(survfit(Surv(time, event) ~ group, data = g4),
main = "Grade IV Glioma" , ylab = "Probability" ,
lty = c(2, 1), xlab = "Survival Time in Month",
xlim = c(0, max(glioma$time) * 1.05))