#include<stdio.h>
#include<string.h>
#include<stdlib.h>

int main() {
	int top, stack[101];
	char input[8];

	top = 0;
	while (scanf("%s", input) != EOF) {
		if ('+' == input[0]) {
			top--;
			stack[top] += stack[top + 1];
		}
		else if ('-' == input[0]) {
			top--;
			stack[top] -= stack[top + 1];
		}
		else if ('*' == input[0]) {
			top--;
			stack[top] *= stack[top + 1];
		}
		else {
			top++;
			stack[top] = atoi(input);
		}
	}
	printf("%d\n", stack[top]);

	return 0;
}
