#include <stdio.h>

int find_index(int target, int ps[], int ptrs[], int n){
  int cur=ps[ptrs[n]]-ps[0];
  while(cur<target){
    ptrs[n]++;
    cur=ps[ptrs[n]]-ps[0];
  }
  return ptrs[n];
}

int find_window(int d, int min, int ps[], int ptrs[]){
  int cur=ps[ptrs[d]+d-1]-ps[ptrs[d]-1];
  while(cur<=min){
    ptrs[d]++;
    cur=ps[ptrs[d]+d-1]-ps[ptrs[d]-1];
  }
  return ptrs[d];
}

int main(void){
  int a1, a2, n, i;
  int args = scanf("%d %d %d",&a1, &a2, &n);
  if (args != 3)
    printf("Failed to read input.\n");

  int a[n];
  a[0]=a1;
  a[1]=a2;

  int ps[n+1];
  ps[0]=0;
  ps[1]=a[0];
  ps[2]=a[0]+a[1];
  for (i=3; i<n+1; i++)
    ps[i] = 1000000;

  int ptrs[n+1];
for(i=0;i<n+1;i++)
    ptrs[i]=1;

  for(i=2;i<n;i++){
    int target=a[i-1]+1;
    int max_len=find_index(target,ps, ptrs, n);
    int cur=ps[max_len]-ps[0];
    int best=cur;

    for(int d=max_len-1;d>1;d--){
      int l=find_window(d, a[i-1], ps, ptrs);
      int cur=ps[l+d-1]-ps[l-1];

      if(cur==target){
        best=cur;
        break;
      }

      if(cur>a[i-1]&&cur<best)
        best=cur;
    }
    a[i]=best;
    ps[i+1]=a[i]+ps[i];
  }

  printf("%d",a[n-1]);
}