#include <bits/stdc++.h>
using namespace std;
typedef pair<int64_t,int64_t> ii;
typedef pair<int64_t,ii> iii;
int64_t T,n,res=0,Count=1,minn=1e18,Num[3],Pre[200005];
ii tree[3][800005];
vector<int64_t> VV;
vector<iii> V;
map<int64_t,int64_t> F;
void Update(int64_t t,int64_t k,int64_t l,int64_t r,int64_t pos,int64_t val,int64_t cnt)
{
if(l==r)
{
tree[t][k].first+=val;
tree[t][k].second+=cnt;
return;
}
int64_t mid=(l+r)/2;
if(pos<=mid)
Update(t,2*k,l,mid,pos,val,cnt);
else
Update(t,2*k+1,mid+1,r,pos,val,cnt);
tree[t][k].first=tree[t][2*k].first+tree[t][2*k+1].first;
tree[t][k].second=tree[t][2*k].second+tree[t][2*k+1].second;
}
int64_t Median(int64_t t,int64_t k,int64_t l,int64_t r,int64_t sum)
{
if(l==r)
return l;
int64_t mid=(l+r)/2;
if(sum+tree[t][2*k].second>=Num[t]/2)
return Median(t,2*k,l,mid,sum);
else
return Median(t,2*k+1,mid+1,r,sum+tree[t][2*k].second);
}
ii Query(int64_t t,int64_t k,int64_t l,int64_t r,int64_t L,int64_t R)
{
if(l>R||L>r)
return ii(0,0);
if(L<=l&&r<=R)
return tree[t][k];
int64_t mid=(l+r)/2;
ii rs,rs1=Query(t,2*k,l,mid,L,R),rs2=Query(t,2*k+1,mid+1,r,L,R);
return ii(rs1.first+rs2.first,rs1.second+rs2.second);
}
int main()
{
ios_base::sync_with_stdio(false);
//freopen("TEST.INP","r",stdin);
cin>>T>>n;
char c1,c2;
int64_t t1,t2;
while(n--)
{
cin>>c1>>t1>>c2>>t2;
if(c1==c2)
res+=abs(t1-t2);
else
{
res++;
V.push_back(iii(t1+t2,ii(t1,t2)));
VV.push_back(t1);
VV.push_back(t2);
}
}
if(V.size()==0)
{
cout<<res;
return 0;
}
sort(VV.begin(),VV.end());
F[VV[0]]=1;
Pre[1]=VV[0];
for(int64_t i=1; i<VV.size(); i++)
if(VV[i]>VV[i-1])
{
Pre[++Count]=VV[i];
F[VV[i]]=Count;
}
sort(V.begin(),V.end());
for(int64_t i=0; i<V.size(); i++)
{
Update(2,1,1,Count,F[V[i].second.first],V[i].second.first,1);
Update(2,1,1,Count,F[V[i].second.second],V[i].second.second,1);
}
Num[2]=V.size()*2;
for(int64_t i=0; i<V.size(); i++)
{
Update(1,1,1,Count,F[V[i].second.first],V[i].second.first,1);
Update(1,1,1,Count,F[V[i].second.second],V[i].second.second,1);
Update(2,1,1,Count,F[V[i].second.first],-V[i].second.first,-1);
Update(2,1,1,Count,F[V[i].second.second],-V[i].second.second,-1);
Num[1]+=2;
Num[2]-=2;
int64_t t1=Median(1,1,1,Count,0);
int64_t t2=Median(2,1,1,Count,0);
int64_t sum=0;
ii rs1=Query(1,1,1,Count,1,t1),rs2=Query(1,1,1,Count,t1,Count);
sum+=Pre[t1]*rs1.second-rs1.first+rs2.first-Pre[t1]*rs2.second;
rs1=Query(2,1,1,Count,1,t2),rs2=Query(2,1,1,Count,t2,Count);
sum+=Pre[t2]*rs1.second-rs1.first+rs2.first-Pre[t2]*rs2.second;
if(T==2||(T==1&&i==V.size()-1))
minn=min(minn,sum);
}
cout<<res+minn;
}
