func: function contribution(uint256 amount)internal returns(int highlow){
          owner.transfer(msg.value);
          totalContribution += msg.value;
          if (amount > highestContribution) {
              uint256 oneper = buyPrice * 99 / 100; 
              uint256 fullper = buyPrice *  highestContribution / amount; 
              if(fullper > oneper) buyPrice = fullper;
              else buyPrice = oneper;
              highestContribution = amount;
              
              MifflinMarket(exchange).highContributionAward(msg.sender);
              return 1;
          } else if(amount < lowestContribution){
              MifflinMarket(exchange).lowContributionAward(msg.sender);
              lowestContribution = amount;
              return -1;
          } else return 0;
      }