#include<iostream>
using namespace std;
int a[100][102];
int len[100];
void add(int k){
     int i,t;
     for(i=0;i<len[k-1];i++)
         a[k][i]=a[k-1][i]+a[k-2][i]+a[k-3][i];
     for(i=0;i<len[k-1];i++)
         if(a[k][i]/10>0){
            a[k][i+1]+=a[k][i]/10;
            a[k][i]%=10;
         }
     if(a[k][i]!=0)
        len[k]=i+1;
     else
        len[k]=i;
     if(len[k]==0)
        len[k]=1;
}      
int main(){
    int b[3],i,j;
    while(scanf("%d %d %d",&b[0],&b[1],&b[2])!=EOF){
         memset(a,0,sizeof(a));
         for(i=0;i<3;i++){
             j=0;
             while(b[i]){
                a[i][j]=b[i]%10;
                b[i]=b[i]/10;
                j++;
             }
             len[i]=j;
             if(len[i]==0)
                len[i]=1;
         }
     for(i=3;i<=99;i++)
             add(i);
     for(i=len[99]-1;i>=0;i--)
         printf("%d",a[99][i]);
         printf("\n");        
     }
    return 0;
}