import std;

void main () {
    int N, W; readln.read(N, W);
    int[] v = new int[](N);
    int[] w = new int[](N);
    foreach (i; 0..N) {
        readln.read(v[i], w[i]);
    }

    int ans = -1;

    foreach (i; 0..N) {
        if (w[i] <= W && ans < v[i]) {
            ans = v[i];
        }
    }

    writeln(ans);
}

void read(T...)(string S, ref T args) {
    auto buf = S.split;
    foreach (i, ref arg; args) {
        arg = buf[i].to!(typeof(arg));
    }
}