#include <stdio.h>
#include <ctype.h>

int stack[102]; int top;
char buf[2000];

int main()
{
	int  v1, v2;
	char *p;

	fgets(p=buf, 500, stdin);
	top = 0;
	while (*p >= ' ') {
		while (isspace(*p)) p++;
		if (isdigit(*p)) {
			v1 = 0;
			while (isdigit(*p)) v1 = 10*v1 + (*p++ & 0xf);
			stack[top++] = v1;
		} else {
			v1 = stack[--top];
			v2 = stack[--top];
			if      (*p == '+') v2 += v1;
			else if (*p == '-') v2 -= v1;
			else if (*p == '*') v2 *= v1;
			stack[top++] = v2;
			p++;
		}
	}
	printf("%d\n", stack[--top]);
	return 0;
}

