One question of C


why the answer is 12 13 13?

[code]

#include <stdio.h>
int x;
int m1(void);
int c1(int x);

int main(void){
int x= 10;
x++;
c1(x);
x++;
m1();
printf("%d\t",x);

x++;
c1(x);
printf("%d\t",x);
m1();
printf("%d\n",x);
return 0;
}
int m1(void){
return (x+=10);
}
int c1(int x){
return (x+=1);
}

[code end]

--

A za a za fighting!
.