///////////////////////////////////Pre-Written Code/////////////////////////////
#include <string.h>
#include <stdio.h>
#include <vector>
#include <queue>
#include <iostream>
#include <algorithm>
#include <stdlib.h>
#include <math.h>
#include <numeric>
#include <map>
#include <set>
#include <sstream>
#include <functional>

using namespace std;
#define all(c) c.begin(),c.end()
#define rep_(i,n) for(i=n-1;i>=0;i--)
#define rep(i,n) for(i=0;i<n;i++)
#define forr(i,a,b) for(i=a;i<=b;i++)
#define forr_(i,a,b) for(i=a;i>=b;i--)
#define min(a,b) ( a>b? b : a )
#define max(a,b) ( a>b? a : b )
#define sz size()
#define pb(a) push_back(a)
#define mset(a,v) memset(a,v,sizeof(a))
#define f first
#define s second
#define EPS 1e-11

typedef vector<int> vi;
typedef vector<vi> vvi;
typedef map<int,int> mi;
typedef vi::iterator it;
typedef pair<int,int> pii;
typedef vector<pii> vpii;
typedef vector<string> vs;
typedef pair<string,int> psi;
typedef vector<psi> vpsi;
typedef queue<int> qi;
typedef queue<pii> qpii;
typedef unsigned long long ubig;
typedef long long big;
typedef long double bigd;
typedef stringstream ss;
template<class T> string tos(T x){stringstream ss;  ss<<x; return ss.str();}
void rot(vvi v,vvi& tmp,int r1,int c1,int r2,int c2)
{
    tmp.resize(c2-c1+1);
    int i,j;
    rep(i,tmp.sz)
        tmp[i].resize(r2-r1+1);
    forr(i,r1,r2)
        forr(j,c1,c2)
            tmp[j-c1][tmp[0].sz-(i-r1)-1]=v[i][j];
}
bool isPal(string s)
{
    int i=0,j=s.sz-1;
    while(i<j)
    {
        if(islower(s[i]) && islower(s[j]) && s[i]!=s[j])
            return false;
        i++; j--;
    }
    return true;
}
///////////////////////////////////Pre-Written Code/////////////////////////////

int vis[10000],n,m;

void solve(int box, int stp)
{
    while(box!=0 && box!=n+1)
    {
        vis[box]=true;
        box+=stp;
    }
}
void imp()
{
    cout<<"-1\n";
    exit(0);
}
int main()
{

    mset(vis,0);
    int i,j;
    cin>>n>>m;
    string s,dir;
    char c;
    int box,stp;

    rep(i,m)
    {
        rep(j,3)cin>>dir;
        cin>>s>>box;
        if( dir=="left" )
            stp=1;
        else
            stp=-1;
        solve( box, stp );
    }
    int res=0;
    forr(i,1,n)if( !vis[i] )res++;

    if( !res ) imp();

    cout<<res<<endl;
}