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

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

int top, S[1000];

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

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

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

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


    } else {
      x = atoi(s);
      push(x);

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

  return 0;
}

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

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


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

//int S[100],top = 0;

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

  while( scanf("%s", s) != EOF ){
    if ( s[0] == '+' ){
      y = S[top--];
      y += S[top--];
      S[++top] = y;

    } else if ( s[0] == '-' ){
      y = S[top--];
      y = -1*y + S[top--];
      S[++top] = y;

    } else if ( s[0] == '*' ){
      y = S[top--];
      y *= S[top--];
      S[++top] = y;

    } else {
      x = atoi(s);
      S[++top] = x;

    }
  }
  //x = atoi(S[top--]);
    x = S[top];

  printf("%d\n",x);

  return 0;
}

