#include<stdio.h>
#include<ctype.h>
 
void push(int);
int pop();
 
int top = 0; 
int S[101];
 
int main(){
 
  char A[100];
  int i, j;
 
  while(scanf("%s",A) != EOF){
    //printf("%d %d\n",top,A[top]);
    //fflush(stdout);
    if(isdigit(A[0])){
      push(atoi(A));
    }
    else{
       
      i = pop();
      j = pop(); 
  
      if(A[0] == '+')
    push( i + j);
      else if(A[0] =='-')
    push( j - i);
      else if (A[0] == '*')
    push (i * j);
      }
  }
 
  printf("%d\n",pop()  );
 
  return 0;
}
 
int pop(){
  return S[--top + 1];
}
 
void push(int x){
  //printf("%d %d\n",top,S[top]);
  // fflush( stdout );
  S[++top] = x;
}