#pragma region
// *INDENT-OFF*
#ifndef M207
#pragma GCC target("popcnt")
#endif
#include <bits/stdc++.h>
using namespace std;
#define il inline
#define fi first
#define se second
#define mp make_pair
#define gcd __gcd
#define pb emplace_back
#define solid const auto &
#define gm int mid((l+r)/2)
#define space putchar(' ')
#define enter putchar('\n')
#define rd() ({int t;in(t);t;})
#define Size(x) ((int)x.size())
#define mem(x,y) memset(x,y,sizeof(x))
// #define ri register int
typedef long long LL;
typedef unsigned int uint;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<LL, LL> pll;
template<class T, class = typename enable_if<is_integral<T>::value>::type>il void in(T &x) {
    x = 0; char c = getchar(); bool f = 0;
    while(!isdigit(c)) f |= (c == '-'), c = getchar();
    while(isdigit(c)) x = x * 10 + (c^'0'), c = getchar();
    f ? x = -x : 0;
}
template<class T, class = typename enable_if<is_integral<T>::value>::type>il void out(T x, const char c = '\n') {
    static short st[40]; short m = 0;
    if(x < 0) putchar('-'), x = -x;
    do st[++m] = x % 10, x /= 10; while(x);
    while(m) putchar(st[m--] | '0');
    putchar(c);
}
template<class T>il void err(const T &x, const char c = '\n') {cerr << x << c;}
template<class T, class ...Args>il void in(T &x, Args &...args) {in(x); in(args...);}
template<class T, class ...Args>il void out(const T &x, const Args &...args) {out(x, ' '); out(args...);}
template<class T, class ...Args>il void err(const T &x, const Args &...args) {err(x, ' '); err(args...);}
template<class T>il void prt(T a, int n) {--n; for(int i = 0; i < n; ++i) out(a[i], ' '); out(a[n], '\n');}
template<class T>il void errprt(T a, int n) {--n; for(int i = 0; i < n; ++i) err(a[i], ' '); err(a[n], '\n');}
template<class T>il void clr(T a[], int n) {memset(a, 0, sizeof(T)*n);}
template<class T>il void clr(T *a, T *b) {memset(a, 0, sizeof(T) * (b - a));}
template<class T>il bool ckmax(T &a, const T &b) {return a < b ? a = b, 1 : 0;}
template<class T>il bool ckmin(T &a, const T &b) {return a > b ? a = b, 1 : 0;}
namespace MOD_CALC
{
const int md = 1e9 + 7, inv2 = (md + 1) / 2;
il int add(const int a, const int b) {return a + b >= md ? a + b - md : a + b;}
il int sub(const int a, const int b) {return a - b < 0 ? a - b + md : a - b;}
il int mul(const int a, const int b) {return (LL)a * b % md;}
il void inc(int &a, const int b) {(a += b) >= md ? a -= md : 0;}
il void dec(int &a, const int b) {(a -= b) < 0 ? a += md : 0;}
il int qpow(int a, int b) {int r = 1; for(; b; b >>= 1, a = mul(a, a)) if(b & 1) r = mul(r, a); return r;}
il int qpow(int a, int b, const int p) {int r = 1; for(; b; b >>= 1, a = (LL)a * a % p) if(b & 1) r = (LL)r * a % p; return r;}
il int mdinv(const int a) {return qpow(a, md - 2);}
template<class ...Args>il int add(const int a, const int b, const Args &...args) {return add(add(a, b), args...);}
template<class ...Args>il int mul(const int a, const int b, const Args &...args) {return mul(mul(a, b), args...);}
} //using namespace MOD_CALC;
namespace i207M
{
// *INDENT-ON*
#pragma endregion

//建立结构体


//建立变量
const int N = 1e5 + 5;
int n;
LL f[N],m;
int s[N],minn = 0x3f3f3f3f;
int st[N][20];

//建立函数
void init()
{
	for(int i = 1;i <= n;i ++)
	{
		st[i][0] = s[i];
		f[i] += f[i - 1];
	}
	for(int j = 1;(1 << j) <= n;j ++)
	{
		for(int i = 1;i + (1 << j) - 1 <= n;i ++)
		{
			st[i][j] = max(st[i][j - 1],st[i + (1 << (j - 1))][j - 1]);
		}
	}
}

int query(int l,int r)
{
	int k = 31 - __builtin_clz(r - l + 1);
//	int k = int(log2(r - 1 + 1));
//	cout<<"B"<<l<<" "<<r<<" "<<k<<" "<<r-l+1<<endl;
	return max(st[l][k],st[r - (1 << k) + 1][k]);
}

void check(int l,int r)
{
	if(f[r] - f[l - 1] >= m)
	{
		int bj = query(l,r);
		minn = min(minn,bj);
	}
}
signed main()
{
#ifdef M207
    // freopen("in.in", "r", stdin);
    // freopen("ot.out","w",stdout);
#endif
	//do at there
	in(n,m);
	for(int i=1;i<=n;++i) in(f[i],s[i]);
	init();
	for(int l = 1;l <= n;l ++)
	{
		for(int r = l;r <= n;r ++)
		{
			check(l,r);
		}
	}
	out(minn);
	return 0;
}
#pragma region
}
signed main()
{
	i207M::main();
    return 0;
}
#pragma endregion

只知道是n^2的复杂度，求求各位大佬帮忙改成一下时间复杂度