#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;
}
