#include<iostream.h>

long numar(long x, int c1,int c2)
{ long r=0;
  while(x)
  { if(x%10==c1) r=r*10+c2;
    else r=r*10+x%10;
    x=x/10;
  }
  while(r)
  { x=x*10+r%10;
    r=r/10;
  }
  return x;
}

int rec(int x, int c1, int c2)
{ if(x==0) return 0;
  else if(x%10==c1) return rec(x/10,c1,c2)*10+c2;
       else return rec(x/10,c1,c2)*10+x%10;
}

void main()
{ long x;
  cin>>x;
  cout<<rec(x,4,7);
}