P1088:iguana

#include<bits/stdc++.h>
using namespace std;

typedef long long int ll;

struct elem{
    ll index;
    ll stats;
    bool operator < (const elem& rhs)const
    {
        return index < rhs.index;
    }
};

ll cost(ll food,ll now){
    for(int i = 0 ; i <= 2 ; i ++){
        if((now+i)%3 == food)return i;
    }
    printf("Error");
    return -1;
}

int main()
{
    //freopen("input.txt","r",stdin);
    ll n,m;
    scanf("%lld %lld",&n,&m);
    vector<elem> vec;
    for(ll i = 0 ; i < m ; i ++){
        ll a,b;
        scanf("%lld %lld",&a,&b);
        vec.push_back({a,1});
        vec.push_back({b+1,-1});
    }
    vec.push_back({n+1,0});
    char c;
    scanf(" %c",&c);
    ll food;
    if(c == 'R')food = 0;
    else if(c == 'G')food = 1;
    else if(c == 'B')food = 2;
    sort(vec.begin(),vec.end());
    /*printf("Test vec : ");
    for(ll i = 0 ; i < vec.size() ; i ++)printf("(%d,%d) ",vec[i].index,vec[i].stats);
    printf("\n");*/
    vector<elem> vec2;
    for(ll i = 0 ; i < vec.size() ; ){
        ll j = i;
        ll sum = 0;
        while(j < vec.size() && vec[j].index == vec[i].index){
            sum += vec[j].stats;
            j++;
        }
        vec2.push_back({vec[i].index,sum});
        i = j;
    }
/*  printf("Test vec2 : ");
    for(ll i = 0 ; i < vec2.size() ; i ++){
        printf("(%lld,%lld) ",vec2[i].index,vec2[i].stats);
    }
    printf("\n");*/
    ll prev = 1;
    ll now = 0;
    ll ans = 0;
    for(ll i = 0 ; i < vec2.size() ; i ++){
        ll len = vec2[i].index - prev;
        ans += len*cost(food,now%3);
        now += vec2[i].stats;
        prev = vec2[i].index;
    /*  int sum = 0
        int j = i;
        while(j < vec.size() && vec[j].index ==)*/
    }
    printf("%lld",ans);
    return 0;
}