17 lines
269 B
C
17 lines
269 B
C
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#include <stdio.h>
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int main(void){
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int n;
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while(scanf("%d",&n) && ~n){
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int last = 0, mile = 0;
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for(int i = 0; i < n; i++){
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int now, speed;
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scanf("%d %d",&speed,&now);
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mile += speed * (now-last);
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last = now;
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}
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printf("%d\n",mile);
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}
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return 0;
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}
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