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

int top, S[1000];
int pop();
void push(int);

int main()
{
  int a,b;
  top = 0;
  char s[100];
  while(scanf("%s",s) != EOF){
    if(s[0] == '+'){
      a = pop();
      b = pop();
      push(a+b);
    }
    else if(s[0] == '-'){
      a = pop();
      b = pop();
      push(a-b);
    }
    else if(s[0] == '*'){
      a = pop();
      b = pop();
      push(a*b);
    }
    else
      push(atoi(s));
  }

  printf("%d\n",pop());
  return 0;
}

void push(int x){
  S[++top] = x;
}

int pop(){
  top--;
  return S[top+1];
}


