#include<cstdio>
#include<algorithm>
using namespace std;
typedef long long ll;
const int N=100010,M=455,BUF=2500000;
const ll inf=1LL<<62;
char Buf[BUF],*buf=Buf;
int n,m,type,block,i,id,lim,pos[N],st[M],en[M],L[M],R[M],q[N],pre[M];ll tag[M];
bool v[N];int f[N];ll g[N],tmp,ans,old;
struct P{ll k,b,a;}a[N];
inline bool cmp(const P&a,const P&b){return a.k>b.k;}
inline void read(int&a){for(a=0;*buf<48;buf++);while(*buf>47)a=a*10+*buf++-48;}
inline double cross(const P&a,const P&b){return 1.0*(b.b-a.b)/(a.k-b.k);}
inline void build(int x){int l=st[x],r=en[x],t=l-1;for(int i=l;i<=r;i++)if(!v[i]){if(t>=l&&a[q[t]].k==a[i].k)if(a[q[t]].b<=a[i].b)continue;else t--;while(t>l&&cross(a[i],a[q[t]])<cross(a[q[t]],a[q[t-1]]))t--;q[++t]=i;}L[x]=l,R[x]=t;
}
inline void query(int x){int&i=L[x],j=R[x],X=pre[x];ll B=tag[x];if(i>j)return;for(;i<j;i++)if(a[q[i]].k*X+a[q[i]].b<a[q[i+1]].k*X+a[q[i+1]].b)break;ll t=a[q[i]].k*X+a[q[i]].b+B;if(t<tmp)tmp=t,id=i;
}
inline void choose(){int i;tmp=inf;for(i=0;i<=block;i++)query(i);ans+=tmp;int x=q[id],y=pos[x],l=st[y],r=en[y];ll k=a[x].k;v[x]=1;for(i=y+1;i<=block;i++)pre[i]++;for(i=y-1;~i;i--)tag[i]+=k;for(i=x-1;i>=l;i--)a[i].b+=k;for(i=x+1;i<=r;i++)a[i].b+=a[i].k;build(y);
}
inline void build2(int x){int l=st[x],r=en[x],t=l-1;for(int i=l;i<=r;i++)if(v[i]){if(t>=l&&a[q[t]].k==a[i].k)if(a[q[t]].b>=a[i].b)continue;else t--;while(t>l&&cross(a[i],a[q[t]])>cross(a[q[t]],a[q[t-1]]))t--;q[++t]=i;}L[x]=l,R[x]=t;
}
inline void query2(int x){int&i=L[x],j=R[x],X=pre[x];ll B=tag[x];if(i>j)return;for(;i<j;i++)if(a[q[i]].k*X+a[q[i]].b>a[q[i+1]].k*X+a[q[i+1]].b)break;ll t=a[q[i]].k*X+a[q[i]].b+B;if(t>tmp)tmp=t,id=i;
}
inline void choose2(){int i;tmp=-inf;for(i=0;i<=block;i++)query2(i);ans-=tmp;int x=q[id],y=pos[x],l=st[y],r=en[y];ll k=a[x].k;v[x]=0;for(i=y+1;i<=block;i++)pre[i]--;for(i=y-1;~i;i--)tag[i]-=k;for(i=x-1;i>=l;i--)a[i].b-=k;for(i=x+1;i<=r;i++)a[i].b-=a[i].k;build2(y);
}
int main(){fread(Buf,1,BUF,stdin);read(n),read(m),read(type);for(i=0;i<n;i++){int x,y;read(x),read(y);a[i].a=a[i].b=x,a[i].k=y;}sort(a,a+n,cmp);while(lim*lim*2<n)lim++;for(i=0;i<n;i++)pos[i]=i/lim;for(i=0;i<n;i++)en[pos[i]]=i;for(i=n-1;~i;i--)st[pos[i]]=i;block=pos[n-1];if(m+m<=n){for(i=0;i<=block;i++)build(i);for(i=0;i<m;i++)choose();}else{for(i=0;i<n;i++)v[i]=1;for(i=n-1;~i;i--)a[i].b+=tmp,tmp+=a[i].k,ans+=a[i].b;for(i=0;i<n;i++)a[i].b+=a[i].k*i;for(i=0;i<=block;i++)build2(i);for(i=0;i<n-m;i++)choose2();}if(!type)return printf("%lld",ans),0;old=ans;for(i=0;i<n;i++)if(v[i])ans=min(ans,old-a[i].a);for(i=0;i<n;i++){if(i)f[i]=f[i-1];if(v[i])f[i]++;}for(i=n-1;~i;i--){g[i]=g[i+1];if(v[i])g[i]+=a[i].k;}for(i=0;i<n;i++)if(v[i])f[i]--,g[i]-=a[i].k;tmp=inf;for(i=0;i<n;i++)if(v[i])tmp=min(tmp,-a[i].k*f[i]-a[i].a-g[i]);else if(tmp<inf)ans=min(ans,old+tmp+a[i].k*(f[i]-1)+g[i]);tmp=inf;for(i=n-1;~i;i--)if(v[i])tmp=min(tmp,-a[i].k*(f[i]+1)-a[i].a-g[i]);else if(tmp<inf)ans=min(ans,old+tmp+a[i].k*f[i]+g[i]);return printf("%lld",ans),0;
}