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

int top, S[100];

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

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

int main(void){
  int a,b;
  top = 0;
  char str[11];
  while(scanf("%s", str) != EOF){
    if(str[0] == '+'){
      a = pop();
      b = pop();
      push(b + a);
    } else if (str[0] == '-'){
      a = pop();
      b = pop();
      push(b - a);
    } else if (str[0] == '*'){
      a = pop();
      b = pop();
      push(b * a);
    } else {
      push(atoi(str));
    }
  }
  printf("%d\n", pop());
  return 0;
}
