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

int top, S[1000];

void push(int x){
	top ++; 
	S[top] = x;
}
int pop(){
	top--;
	return S[top+1];
}

int main (void){
		int a,b;
	top = 0;
	char s [ 100 ];
	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;
}

