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#include <bits/stdc++.h>
using namespace std;
typedef vector<int> VI;
typedef pair <int,int> ii;
typedef long long LL;
typedef pair <LL,LL> pll;
#define pb push_back
const int INF = 2147483647;
const int N = 500005;

LL n, s, a, b, res;
int m, i;
vector<pll> v;

void check(LL x) {
	LL a = labs(res - s);
	LL b = labs(x - s);
	if (b < a) res = x;
}

int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
cin >> n >> m >> s;
while (m--) {
	cin >> a >> b;
	v.pb(pll(a, b));
}
v.pb(pll(0, 0));
v.pb(pll(n + 1, n + 1));
sort(v.begin(), v.end());

res = INF * 1LL * INF;
for (i=1;i<(int)v.size() - 1;i++) {
	if (v[i].first - 1 != v[i - 1].second) check(v[i].first - 1);
	if (v[i].second + 1 != v[i + 1].first) check(v[i].second + 1);
}
cout << res << endl;
return 0;
}