#include <cstdio>

using namespace std;

long n,m,k,v[100010],x[100010],i,j;

int main(){
freopen("stergeri.in","r",stdin);
freopen("stergeri.out","w",stdout);
scanf("%ld%ld%ld",&m,&n,&k);
for (i=1;i<=n;i++)
    scanf("%ld%ld",&v[i],&x[i]);    
for (i=n;i>=1;i--)
    if (v[i]<=k)        
        k+=(x[i]-v[i]+1);
printf("%ld\n",k);
return 0;
}