操作系统前驱图例题

1、根据下面程序段包含的语句，画出它的前趋图。

int a,b,c,d,e;
int u,v,w,x,y,z;

S1: u = a+b;
S2: v = (c-d)*e;
S3: w = u+a;
S4: x = u-v;
S5: y = w*x;
S6: z = y/e;