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

int top, S[1000];

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

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

int main() {
    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;
}
