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

int top,stack[1000];

void push(int);
int pop();

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){
  stack[++top] = x;
}

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

