/* a ridiculously simplified "virtual machine" */

#include <stdint.h>
#include <stdio.h>

/* convert four int8_t values into a single int32_t value */
static int32_t bytes_to_int(int8_t a, int8_t b, int8_t c, int8_t d) {
	return
		  (((int32_t)a & 0xff) << 0)
		| (((int32_t)b & 0xff) << 8)
		| (((int32_t)c & 0xff) << 16)
		| (((int32_t)d & 0xff) << 24);
}

/* the stack of the virtual machine */
int32_t stack [256];

/* the interpreter for the vm */
/* FREESTYLE OPTIMIZATIONS */
int vm(const char *insns) 
{
	int pc = 0;
	int sp = 0;
	
	while (insns[pc] != '\0')
		{
			int8_t op = insns[pc];
			int32_t t;

			printf("pc: %d op: %c\n", pc, op);
			/* putchar(op); */

			/* printf(" %d/%d:\t%08x\t%08x\t%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", */
			/* 	   pc, sp, */
			/* 	   stack[0], stack[1], stack[2], stack[3], */
			/* 	   stack[4], stack[5], stack[6], stack[7]); */

			switch (op)
				{
				case '0':
				case '1':
				case '2':
				case '3':
				case '4':
				case '5':
				case '6':
				case '7':
				case '8':
				case '9':
					stack[sp] = op-'0';
					sp++;
					break;
				case 'I': /* immediate */
					stack[sp] = bytes_to_int(insns[pc+1], insns[pc+2], insns[pc+3], insns[pc+4]);
					pc += 4;
					sp++;
					break;
				case 'D': /* dup */
					stack[sp] = stack[sp-1];
					sp++;
					break;
				case 'X': /* exchange */
					t = stack[sp-1];
					stack[sp-1] = stack[sp-2];
					stack[sp-2] = t;
					break;
				case 'P': /* pop */
					sp--;
					break;
				case '+': /* add */
					sp--;
					stack[sp-1] = stack[sp-1] + stack[sp];
					break;
				case '-': /* subtract */
					sp--;
					stack[sp-1] = stack[sp-1] - stack[sp];
					break;
				case '*': /* multiply */
					sp--;
					stack[sp-1] = stack[sp-1] * stack[sp];
					break;
				case '~': /* not */
					stack[sp-1] = ~stack[sp-1];
					break;
				case '<': /* less than */
					sp--;
					stack[sp-1] = stack[sp-1] < stack[sp] ? -1 : 0;
					break;
				case 'J': /* jump if true */
					sp--;
					if (stack[sp] != 0) {
						pc += (int8_t)insns[pc+1];
					} else {
						pc++;
					}
					break;
				default:
					/* ignore everything else */
					break;
				}
			pc++;
		}

	/* printf("  %d/%d:\t%08x\t%08x\t%08x\t%08x\t%08x\t%08x\t%08x\t%08x\n", */
	/* 	   pc, sp, */
	/* 	   stack[0], stack[1], stack[2], stack[3], */
	/* 	   stack[4], stack[5], stack[6], stack[7]); */

	return stack[sp-1];
}

int main() {

	/* BENCHMARK START */
	/* you don't need to understand that code, the answer is '6' */
	int retval = vm(
"48*88*\
X1-X\
D+\
DJ\xf8\
P68*+\
DI\040\0\0\0\
<~J\005\
P88*");	
	/* BENCHMARK END */

	putchar(retval);
	
	return retval;
}