#include <stdio.h>
#include <assert.h>

typedef struct{
    int pc,n;
    char from,to,via;
}Frame;

#define call(...) ({*(++top)=(Frame){.pc=0,__VA_ARGS__};})
#define ret() ({top--;})
#define goto(loc) ({f->pc=(loc)-1;})

void hanoi(int n,char from,char to,char via){
    Frame stk[64],*top=stk-1;
    call(n,from,to,via);
    Frame* f;
    for(;(f=top)>=stk;f->pc++){
        switch (f->pc)
        {
        case 0:
            if(f->n==1){
            	printf("move from %c to %c\n",f->from,f->to);
            	goto(4);
			}
            break;
        case 1:
            call(f->n-1,f->from,f->via,f->to);
            break;
        case 2:
            call(1,f->from,f->to,f->via);
            break;
        case 3:
            call(f->n-1,f->via,f->to,f->from);
            break;
        case 4:
            ret();
        default:
            assert(0);
        }
    }
}

int main(){
    hanoi(3,'A','C','B');
}