#include<stdio.h>
#define dim 100001
using namespace std;

long long a[dim],v[dim];

void qsort(int in,int sf)   
    {long i,j;   
     long temp,aux;   
     i=in,j=sf;   
     temp=a[(i+j)>>1];   
        
     do  
       {while(a[i]<temp)i++;   
        while(a[j]>temp)j--;   
        if(i<j) {aux=a[i],a[i]=a[j],a[j]=aux; aux=v[i],v[i]=v[j],v[j]=aux;}  
        if(i<=j)j--,i++;   
        } while(i<=j);   
     if(in<j)qsort(in,j);   
     if(i<sf)qsort(i,sf);   
     }   

 int main()
 { long long n,m,k,i;
	 
	 FILE *f = fopen("stergeri.in", "r");
	 FILE *g = fopen("stergeri.out", "w");
	
	 fscanf(f, "%lld%lld%lld", &n, &m, &k);
	 
	 for(i = 1; i <= m; i ++)
		 fscanf(f, "%lld%lld", &a[i], &v[i]);
		 
	 qsort(1, m);
	 
	 for(i = 1; i <= m; i++)
		 if(a[i] <= k) k += v[i]-a[i]+1; 
				 
	 fprintf(g, "%lld\n", k);
	 
	 fclose(f);
	 fclose(g);
	 return 0;
 }