#include <stdio.h> int main(){ long long a,b; while(scanf("%lld %lld",&a,&b)!=EOF){ long long i,sum=0,swap; if(a>b){ swap=a; a=b; b=swap; } for(i=a+1;i<b;i++){ if(i==2) sum+=2; else if(i%2==0) continue; if(f(i)==1) sum+=i; } printf("%lld\n",sum); } } int f(int n){ int i; for(i=2;i<=n/2;i++){ if(n%i==0) break; } if(i>n/2) return 1; else return 0; } |
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