#include<stdio.h>
#include<stdlib.h>
#include <string.h>
#include<math.h>
#define scani(x) scanf("%d",&x)
#define scanc(x) scanf("%s",x)

#define printi(x) printf("%d",x)
#define printin(x) printf("%d\n",x)
#define printc(x) printf("%s",x)
#define repd(i,n,m) for(int i = n; i > m; i--)
#define repu(i,n,m) for(int i = 0; i < m; i++)
#define allprintu(i,n,m,a) for(int i = 0; i < m; i++){if(i != m-1){printf("%d ",a[i]);}else{printf("%d\n",a[i]);}}
#define allprintd(i,n,m,a) for(int i = n; i > m; i--){if(i != 0){printf("%d ",a[i]);}else{printf("%d\n",a[i]);}}

int top,si[1000];

void push(int x){
	si[++top] = x;
}
int pop(){
	top--;
	return si[top+1];
}

int main(void){
	int a, b;
	top = 0;
	char sc[100];

	while(scanc(sc) != EOF){
		if (sc[0] == '+'){
			a = pop();
			b = pop();
			push(a+b);

		}else if(sc[0] == '-'){
			b = pop();
			a = pop();
			push(a-b);

		}else if(sc[0] == '*'){
			a = pop();
			b = pop();
			push(a*b);
		}else{
			push(atoi(sc));
		}
	}
	printin(pop());
	return 0;
}
