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

int main() {
    int n = 0, m, k, pt = 0, stk[500];
    for (;;) {
        k = getc_unlocked(stdin);
        if (k < '0' || k > '9') break;
        n = n * 10 + k - '0';
    }
    // printf("%d\n", n);
    for (int i = 0; i < n; ++i) {
        // printf("i=%d, n=%d\n", i, n);
        k = getc_unlocked(stdin);
        if (k == '+') {
            --pt;
            stk[pt - 1] += stk[pt];
            getc_unlocked(stdin);
        } else if (k == '-') {
            --pt;
            stk[pt - 1] -= stk[pt];
            getc_unlocked(stdin);
        } else {
            int m = k - 48;
            for (;;) {
                k = getc_unlocked(stdin);
                if (k < '0' || k > '9') break;
                m = n * 10 + k - '0';
            }
            stk[pt++] = m;
        }
    }

    n = 0, m = 0, k = *stk;
    char f[6];
    if (k < 0) {
        m = 1;
        k = -k;
    }
    while (k) {
        f[n++] = k % 10;
        k /= 10;
    }
    if (!n) f[n++] = 0;
    if (m) putc_unlocked('-', stdout);
    while (n--) putc_unlocked(f[n] + '0', stdout);

    return 0;
}