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#include <bits/stdc++.h>

int main(){
    std::ios_base::sync_with_stdio(0);
    std::cin.tie(0);
    long long a, c, d, e;
    std::cin >> a;
    std::vector<bool>v(a);
    int b;
    std::cin >> b >> c;
    while(b--){
        std::cin >> d >> e;
        for(long long i = d-1; i < e; i++)v[i] = 1;
    }
    e = -1;
    for(long long i = c-2;i >= 0;i--){
        if(v[i] == 0){
            e = i+1;
            break;
        }
    }
    d = -1;
    for(long long i = c;i < v.size();i++){
        if(v[i] == 0){
            d = i+1;
            break;
        }
    }
    if(d == -1)std::cout << e;
    else if(e == -1)std::cout << d;
    else{
        if(d-c == c-e){
            std::cout << e;
        }
        else if(d-c < c-e){
            std::cout << d;
        }
        else std::cout << e;
    }
    return 0;
}