#include<stdio.h>
int main(void)
{
int A,B,S,box[],count;
scanf("%d",&A);
scanf("%d",%B);
scanf("%d",%S);
box[]=S;
count=sizeof box/sizeof(int);
if(1<=A && B<=5 && box[A+1]='-' && count=A+B+1)
{
printf("yes");
}
else{
printf("no");
}
return 0;
}