Language: C++

#define ENABLE_DEBUG 1
// Kana's kitchen {{{
#include<bits/stdc++.h>
#define ALL(v) std::begin(v),std::end(v)
#define LOOP(k) for(i64 ngtkana_is_a_genius=0; ngtkana_is_a_genius<(i64)k; ngtkana_is_a_genius++)

using i32 = std::int_least32_t;
using i64 = std::int_least64_t;
using u32 = std::uint_least32_t;
using u64 = std::uint_least64_t;
using usize = std::size_t;

template <class T, class U> using pair = std::pair<U, T>;
template <class T> using diag_pair = std::pair<T, T>;
template <class... Args> using tuple = std::tuple<Args...>;
template <class T> using vec = std::vector<T>;
template <class T> using numr = std::numeric_limits<T>;

#ifdef NGTKANA
#include<debug.hpp>
#else
#define DEBUG(...)(void)0
#endif
/*}}}*/
// mint{{{
template <class ModType> struct modint {
    using value_type = typename ModType::value_type;
    using mint = modint<ModType>;
    using mod_type = ModType;

    static value_type mod() { return ModType::value; }

    private:
    static value_type inverse(value_type x) {
        value_type y=1,u=mod(),v=0;
        while(x){
            value_type q=u/x;
            u-=q*x; std::swap(x,u);
            v-=q*y; std::swap(y,v);
        }
        assert(x==0 && std::abs(y)==mod() && std::abs(u)==1 && std::abs(v)<mod());
        return v<0?v+mod():v;
    }

    public:
    // the member variable
    value_type value;

    // constructors
    modint()=default;
    modint(modint const&)=default;
    modint(modint&&)=default;
    modint& operator=(modint const&)=default;
    modint& operator=(modint&&)=default;
    ~modint()=default;

    template <class T> modint(T t) : value([t] () mutable {
            if ( t <= -static_cast<T>(mod()) || static_cast<T>(mod()) <= t ) t %= mod();
            return t < 0 ? t + mod() : t;
            }()) {}

    // operators
    mint& operator+= (mint y) {
        value += y.value;
        if (mod() <= value) value -= mod();
        return *this;
    }

    mint& operator-= (mint y) {
        value -= y.value;
        if ( value < 0 ) value += mod();
        return *this;
    }

    mint& operator*= (mint y) {
        value = (long long)value * y.value % mod();
        return *this;
    }

    mint& operator/= (mint y) {
        value = (long long)value * inverse(y.value) % mod();
        return *this;
    }

    mint& operator++() { return *this+=1; }
    mint& operator--() { return *this-=1; }
    mint  operator++(int) { mint this_=*this; ++*this; return this_; }
    mint  operator--(int) { mint this_=*this; --*this; return this_; }

    // static member functions
    static mint inv(mint x) { return inverse(x.value); }

    static mint m1pow(long long y) { return y%2?-1:1; }

    static mint pow(mint x, unsigned long long y) {
        mint ans=1;
        for(;y;y>>=1){
            if(y&1ull) ans*=x;
            x*=x;
        }
        return ans;
    }

    // non-member functions
    mint& add_assign(mint y) { return *this+=y; }
    mint& sub_assign(mint y) { return *this-=y; }
    mint& mul_assign(mint y) { return *this*=y; }
    mint& div_assign(mint y) { return *this/=y; }
    mint& inv_assign()       { return *this = inv(*this); }
    mint& pow_assign(unsigned long long y){ return *this = pow(*this, y); }

    mint add(mint y) { mint ans=*this; return ans.add_assign(y); }
    mint sub(mint y) { mint ans=*this; return ans.sub_assign(y); }
    mint mul(mint y) { mint ans=*this; return ans.mul_assign(y); }
    mint div(mint y) { mint ans=*this; return ans.div_assign(y); }
    mint inv()       { mint ans=*this; return ans.inv_assign(); }
    mint pow(unsigned long long y) { return pow(*this, y); }
    mint twice() { return *this + *this; }
    mint square() { return *this * *this; }
    mint cube() { return *this * *this * *this; }

    template <class F> mint map(F const& f){
        value=f(value);
        return *this;
    }
};

template <class T> std::istream&
operator>>(std::istream& is, modint<T>& x) {
    typename modint<T>::value_type y;
    is >> y;
    x = modint<

Compiler output:
a.cc: In function 'std::istream& operator>>(std::istream&, modint<T>&)':
a.cc:132:15: error: template argument 1 is invalid
  132 |     x = modint<
      |               ^
a.cc:132:16: error: expected '}' at end of input
  132 |     x = modint<
      |                ^
a.cc:129:44: note: to match this '{'
  129 | operator>>(std::istream& is, modint<T>& x) {
      |                                            ^
a.cc:132:16: warning: no return statement in function returning non-void [-Wreturn-type]
  132 |     x = modint<
      |                ^