Iguana

/*
    Task    : Iguana
    Author  : Phumipat C. [MAGCARI]
    Language: C++
    Created : 10 October 2022 [21:04]
*/
#include<bits/stdc++.h>
using namespace std;
vector<pair<int ,int > > v;
int main(){
    int n,m,a,b;
    cin >> n >> m;
    for(int i=1;i<=m;i++){
        cin >> a >> b;
        v.push_back({a,1});
        v.push_back({b+1,-1});
    }
    char c;
    cin >> c;
    int want;
    if(c == 'R')        want = 0;
    else if(c == 'G')   want = 1;
    else                want = 2;

    v.push_back({1,0});
    v.push_back({n+1,0});
    sort(v.begin(),v.end());
    int sum = 0,len,current,ans = 0;
    for(int i=0;i<v.size()-1;i++){
        sum+=v[i].second;
        if(v[i].first == v[i+1].first)  continue;
        current = sum%3;
        len = v[i+1].first-v[i].first;
        ans += ((want-current+3)%3)*len;
    }
    cout << ans << '\n';
    return 0;
}