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

int top, S[1000];

void push(int );
int pop(void );

int main(){
  int a, b;
  top = 0;
  char s[1000];

  while( scanf("%s", s) != EOF ){

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

