#include<stdio.h>
#include<stdlib.h>
#include<string.h>
void push(int);
int  pop( );

int main(){
  int x,y;
  int top = 0;
  char s[100];


  while(scanf("%s", s) != EOF ){
    if ( s[0] == '+' ){
      x = pop( );
      y = pop( );
      push(x+y);

    } else if ( s[0] == '-' ){
      y = pop( );
      x = pop( );
      push(x-y);

    } else if ( s[0] == '*' ){
      x = pop( );
      y = pop( );
      push(x*y);

    } else {
      push(atoi(s));

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

int top,S[1000];
void push(int x){
  S[++top] = x;
}

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

