modint_montgomery.cpp

//
// モンゴメリ乗算を用いた modint (mod は 2^62 未満の奇素数)
//
// verified:
//   AOJ 2353 Four Arithmetic Operations
//     http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=2353
//


#include <bits/stdc++.h>
using namespace std;


// montgomery modint (MOD < 2^62, MOD: odd prime number)
struct MontgomeryModInt64 {
    using mint = MontgomeryModInt64;
    using u64 = uint64_t;
    using u128 = __uint128_t;
    
    // static menber
    static u64 MOD;
    static u64 INV_MOD;  // INV_MOD * MOD ≡ 1 (mod 2^64)
    static u64 T128;  // 2^128 (mod MOD)
    
    // inner value
    u64 val;
    
    // constructor
    MontgomeryModInt64() : val(0) { }
    MontgomeryModInt64(long long v) : val(reduce((u128(v) + MOD) * T128)) { }
    u64 get() const {
        u64 res = reduce(val);
        return res >= MOD ? res - MOD : res;
    }
    
    // mod getter and setter
    static u64 get_mod() { return MOD; }
    static void set_mod(u64 mod) {
        assert(mod < (1LL << 62));
        assert((mod & 1));
        MOD = mod;
        T128 = -u128(mod) % mod;
        INV_MOD = get_inv_mod();
    }
    static u64 get_inv_mod() {
        u64 res = MOD;
        for (int i = 0; i < 5; ++i) res *= 2 - MOD * res;
        return res;
    }
    static u64 reduce(const u128 &v) {
        return (v + u128(u64(v) * u64(-INV_MOD)) * MOD) >> 64;
    }
    
    // arithmetic operators
    mint operator + () const { return mint(*this); }
    mint operator - () const { return mint() - mint(*this); }
    mint operator + (const mint &r) const { return mint(*this) += r; }
    mint operator - (const mint &r) const { return mint(*this) -= r; }
    mint operator * (const mint &r) const { return mint(*this) *= r; }
    mint operator / (const mint &r) const { return mint(*this) /= r; }
    mint& operator += (const mint &r) {
        if ((val += r.val) >= 2 * MOD) val -= 2 * MOD;
        return *this;
    }
    mint& operator -= (const mint &r) {
        if ((val += 2 * MOD - r.val) >= 2 * MOD) val -= 2 * MOD;
        return *this;
    }
    mint& operator *= (const mint &r) {
        val = reduce(u128(val) * r.val);
        return *this;
    }
    mint& operator /= (const mint &r) {
        *this *= r.inv();
        return *this;
    }
    mint pow(u128 n) const {
        mint res(1), mul(*this);
        while (n > 0) {
            if (n & 1) res *= mul;
            mul *= mul;
            n >>= 1;
        }
        return res;
    }
    mint inv() const { 
        return pow(MOD - 2); 
    }

    // other operators
    bool operator == (const mint &r) const {
        return (val >= MOD ? val - MOD : val) == (r.val >= MOD ? r.val - MOD : r.val);
    }
    bool operator != (const mint &r) const {
        return (val >= MOD ? val - MOD : val) != (r.val >= MOD ? r.val - MOD : r.val);
    }
    mint& operator ++ () {
        ++val;
        if (val >= MOD) val -= MOD;
        return *this;
    }
    mint& operator -- () {
        if (val == 0) val += MOD;
        --val;
        return *this;
    }
    mint operator ++ (int) {
        mint res = *this;
        ++*this;
        return res;
    }
    mint operator -- (int) {
        mint res = *this;
        --*this;
        return res;
    }
    friend istream& operator >> (istream &is, mint &x) {
        long long t;
        is >> t;
        x = mint(t);
        return is;
    }
    friend ostream& operator << (ostream &os, const mint &x) {
        return os << x.get();
    }
    friend mint pow(const mint &r, long long n) {
        return r.pow(n);
    }
    friend mint inv(const mint &r) {
        return r.inv();
    }
};

typename MontgomeryModInt64::u64
MontgomeryModInt64::MOD, MontgomeryModInt64::INV_MOD, MontgomeryModInt64::T128;



//------------------------------//
// Examples
//------------------------------//

void AOJ2353() {
    using mint = MontgomeryModInt64;
    const long long MOD = 67280421310721LL;
    mint::set_mod(MOD);

    mint res = 0;
    int N;
    cin >> N;
    for (int i = 0; i < N; ++i) {
        long long o, y;
        cin >> o >> y;
        if (o == 1) res += y;
        else if (o == 2) res -= y;
        else if (o == 3) res *= y;
        else res /= y;
    }
    if (res.get() <= 1LL<<31) cout << res.get() << endl;
    else cout << (long long)res.get() - MOD << endl;
}


int main() {
    AOJ2353();
}